  United States Court of Appeals
      for the Federal Circuit
              __________________________

                  MONA PORTER,
                  Petitioner-Appellee,

                           v.
      SECRETARY OF HEALTH AND HUMAN
                 SERVICES,
             Respondent-Appellant.
              __________________________

                      2010-5162
              __________________________

    Appeal from the United States Court of Federal
Claims in case no. 99-VV-639, Judge Nancy B. Firestone.
               __________________________

 AMANDA KNIGHT, PERSONAL REPRESENTATIVE OF
   THE ESTATE OF CLAUDIA J. ROTOLI-BARR,
                   DECEASED,
               Petitioner-Appellee,

                           v.
      SECRETARY OF HEALTH AND HUMAN
                 SERVICES,
             Respondent-Appellant.
              __________________________

                      2010-5163
              __________________________
PORTER   v. HHS                                             2


    Appeal from the United States Court of Federal
Claims in case no. 99-VV-644, Judge Nancy B. Firestone.
               __________________________

                  Decided: November 22, 2011
                  __________________________

    SYLVIA CHIN-CAPLAN, Conway, Homer & Chin-Caplin,
P.C., of Boston, Massachusetts, argued for both petition-
ers-appellees. On the brief was RONALD C. HOMER

    SARANG V. DAMLE, Attorney, Appellate Staff, Civil Di-
vision, United States Department of Justice, of Washing-
ton, DC, argued for respondent-appellant. With him on
the brief were TONY WEST, Assistant Attorney General,
and THOMAS M. BONDY, Attorney.
               __________________________

Before RADER, Chief Judge, PROST and O’MALLEY, Circuit
                       Judges.
   Opinion for the court filed by Circuit Judge PROST.
  Opinion concurring-in-part, dissenting-in-part filed by
                Circuit Judge O’MALLEY.

PROST, Circuit Judge.

     The government appeals the combined decision of the
United States Court of Federal Claims (“Claims Court”)
reversing a special master’s decision denying Mona Por-
ter’s and Claudia Rotoli’s petitions for compensation
under the National Vaccine Injury Compensation Pro-
gram (“Vaccine Act”), 42 U.S.C. §§ 300aa–1 to –34. The
special master concluded that Ms. Porter and Ms. Rotoli
did not prove by a preponderance of the evidence that the
hepatitis B vaccine—which they both received in three
3                                           PORTER   v. HHS


doses in the 1990s—caused them to suffer autoimmune
hepatitis (“AIH”). The Claims Court, incorrectly applying
Andreu v. Secretary of Health & Human Services, 569
F.3d 1367 (Fed. Cir. 2009), set aside the special master’s
findings in their entirety on the ground that the special
master allegedly erred by considering the credibility of
the petitioners’ expert witness. Having rejected the
special master’s findings, the Claims Court entered its
own findings and determined that both Ms. Porter and
Ms. Rotoli were entitled to recover for their AIH under
the Vaccine Act. We conclude that the Claims Court’s
interpretation of Andreu was legally erroneous and incon-
sistent with this court’s precedent. We further conclude
that the special master’s determination that the petition-
ers were not entitled to compensation under the Vaccine
Act was not arbitrary, capricious, an abuse of discretion,
or otherwise not in accordance with law. As such, we
reverse and remand with instructions to affirm the spe-
cial master’s determination that neither petitioner is
entitled to recover under the Vaccine Act.

                      BACKGROUND

                            I

     The two appeals before us present overlapping legal
and factual issues. The first, case number 2010-5162,
concerns petitioner Mona Porter. Ms. Porter was born on
September 28, 1962. The first date in her medical history
that has relevance to this case is May 15, 1991. On that
day, Ms. Porter’s dermatologist prescribed minocycline for
Ms. Porter’s acne. Minocycline is well-known in the
literature to cause AIH. On May 11, 1992, her derma-
tologist indicated that she should “finish off” her mino-
cycline dosage and then discontinue treatment with the
drug.
PORTER   v. HHS                                           4


    On July 8, 1992, Ms. Porter received the first of three
doses of the hepatitis B vaccine. She also had a liver
function blood test that day. Her liver function tests were
within the normal range. Ms. Porter’s second dose was
administered on August 7, 1992. The record does not
indicate whether she had any blood work performed on
that day. Ms. Porter received her final vaccine dose on
February 5, 1993. A liver function test performed on
March 1 revealed that her liver enzymes were elevated
well beyond the normal range. The liver function test was
repeated four days later and yielded comparable results.
Blood tests from this date indicated that Ms. Porter was
immune to hepatitis B and was not infected with hepatitis
A, B, or C.

     On March 11, 1993, Ms. Porter started feeling nause-
ated, itching, and turning yellow. She visited a doctor
who was her employer’s colleague, but the office did not
create a record of this visit. Ms. Porter next saw a gastro-
enterologist, Dr. Richard Gilmore. At the initial visit, Dr.
Gilmore’s impression was that Ms. Porter suffered from
“acute hepatitis of undetermined etiology. The possibility
that this is related to her vaccine cannot be excluded.” He
prescribed a steroid to minimize the body’s immune
response, and requested additional blood work. The blood
work, which was performed on April 1, 1993, was consis-
tent with a diagnosis of AIH. A liver function test showed
that Ms. Porter’s liver enzymes had decreased but were
still above normal. In light of these test results, a liver
biopsy was performed on May 14, 1993. The pathologist
and Dr. Gilmore interpreted the results as being consis-
tent with AIH.

    AIH continued to affect Ms. Porter for several addi-
tional years. On August 4, 1999, she filed a petition
5                                            PORTER   v. HHS


seeking compensation under the Vaccine Act.        See 42
U.S.C. §§ 300aa-I et seq.

     The second appeal, case number 2010-5163, concerns
petitioner Claudia Rotoli. 1 Ms. Rotoli was born on Janu-
ary 25, 1969. As pertinent to this case, Ms. Rotoli’s
medical history began in 1984, a decade before she re-
ceived the hepatitis B vaccine. From March 1984 to
February 1990, Ms. Rotoli was treated for skin rashes,
shoulder pain, and severe anxiety. In addition, Ms. Rotoli
received treatment for anxiety and depression in 1994.
Her symptoms included slow and difficult speech, epi-
sodes of blurred vision, chest pains and difficulty think-
ing. Ultimately, she was treated at a Florida hospital
emergency room for confusion, stuttering, and speech
difficulty. Her examination at that time included a CT
head scan, thyroid profile, and blood count, which were all
normal.

    On October 10, 1994, Ms. Rotoli received the first dose
of the hepatitis B vaccine as well as a flu vaccine. Two
days later, she began to experience coughing, congestion,
and fever. On October 21, 1994, her doctor recommended
that she take cough medicine for these symptoms. She
was given the next dose of the hepatitis B vaccine on
November 9, 1994. She visited her doctor approximately
two months later to be treated for a prolonged upper
respiratory infection, bronchitis, and conjunctivitis. She
further reported that she began to have pain in her “right
upper quadrant” in May 1995. On May 5, 1995, Ms.
Rotoli received her final dose of the hepatitis B vaccine.
Four days later, she donated blood. On May 19, 1995, the


    1   Ms. Rotoli passed away after the Claims Court’s
decision in this case. For simplicity, we continue to refer
to her as the petitioner.
PORTER   v. HHS                                         6


blood service informed her that her donated blood con-
tained an elevated amount of a certain enzyme diagnostic
for some forms of liver disease.

    Ms. Rotoli sought information about her abnormal
liver test results. Blood tests from May 25, 1995 con-
firmed that she had elevated liver enzyme levels. Ms.
Rotoli was diagnosed as having hepatitis of unknown
origin. She saw a general practitioner on May 31, 1995
for a follow up. That doctor noted that Ms. Rotoli had a
slight tremor in her hand, and ordered additional blood
tests, which again confirmed that Ms. Rotoli’s liver func-
tion was not normal. She subsequently saw Dr. Katz, a
gastroenterologist, on June 20, 1995. Dr. Katz thought
that Ms. Rotoli might have either a viral illness or AIH
and ordered additional blood tests. The test results were
consistent with a diagnosis of AIH. On June 29, 1995,
Ms. Rotoli had a liver biopsy. This biopsy showed that
Ms. Rotoli had chronic, active hepatitis with fibrosis and
moderate necrosis. Based on her blood test results and
liver biopsy, Dr. Katz diagnosed Ms. Rotoli as having AIH
and prescribed a steroid to moderate the reaction of her
immune system.

    AIH and other health problems continued to plague
Ms. Rotoli. In October of 1996, she was further diagnosed
with Sjogren’s disease. The following year, she was
diagnosed with systemic lupus erythematosus, another
autoimmune disorder. In 1998, she was diagnosed with
central nervous system lupus. She filed a Vaccine Pro-
gram petition on August 4, 1999, seeking compensation
for her AIH and associated injuries.

                            II

   Ms. Porter’s and Ms. Rotoli’s cases, along with several
7                                             PORTER   v. HHS


other cases in which the petitioners alleged that the
hepatitis B vaccine caused them to suffer from AIH, were
assigned to the same special master in 2006. The parties
agreed to conduct a joint hearing for all of these cases.
The special master heard five days of live testimony over
two separate sessions. The proceedings focused princi-
pally on the competing opinions of the government’s two
experts, Dr. Burton Zweiman, an immunologist, and Dr.
Raymond Koff, a specialist in hepatology, and petitioners’
expert, Dr. Joseph Bellanti, an immunologist. The first
hearing session was held over three days in September
2007. The second two-day session was held many months
later in March 2008. Notably, petitioners did not offer
testimony from an expert in gastroenterology or hepatol-
ogy despite being given an opportunity to do so.

     During the hearing, petitioners’ expert (Dr. Bellanti)
presented a series of theories directed at showing that the
hepatitis B vaccine could cause autoimmune hepatitis.
The government’s experts (Dr. Zweiman and Dr. Koff)
disagreed, explaining that “the evidence does not show
that the hepatitis B vaccine can cause autoimmune hepa-
titis.” Dr. Koff, who offered the only testimony from a
specialist in hepatology, provided further testimony
regarding petitioners’ individual cases. Regarding Ms.
Rotoli, he testified that her June 29, 1995 liver biopsy
(eight-and-a-half months after her first vaccination)
showed such extensive fibrosis that, in his experience, Ms.
Rotoli’s hepatitis had to have predated her vaccination.
Pertaining to Ms. Porter, he opined that her liver prob-
lems were more likely caused by her use of minocycline—
a known cause of AIH—than by the hepatitis B vaccine.

     The special master denied Ms. Porter’s and Ms. Ro-
toli’s petitions, providing alternative rationales for deny-
ing each petitioner’s claim. Porter v. Sec’y of Health &
PORTER   v. HHS                                           8


Human Servs., No. 99-639V, 2008 WL 4483740 (Fed. Cl.
Oct. 2, 2008) (“Special Master Porter Op.”); Rotoli v. Sec’y
of Health & Human Servs., No. 99-644V, 2008 WL
4483739 (Fed. Cl. Oct. 2, 2008) (“Special Master Rotoli
Op.”). 2 After examining Dr. Bellanti’s theories at length,
as well as considering Dr. Zweiman’s and Dr. Koff’s
testimony, the special master concluded that “none of [Dr.
Bellanti’s] theories presents a reliable explanation of how
the hepatitis B vaccine can cause autoimmune hepatitis.”
Special Master Porter Op. at *5. Accordingly, he found by
a preponderance of the evidence that both petitioners had
failed to establish a medical theory causally connecting
the hepatitis B vaccine to AIH. Id. at *15-16. In addition,
the special master specifically found that Ms. Rotoli failed
to establish an appropriate temporal relationship between
her vaccinations and AIH in light of Dr. Koff’s opinion
that her extensive fibrosis could not have developed in
eight months. Special Master Rotoli Op. at *17-18.
Because petitioners’ burden included establishing (1) a
medical theory causally connecting the vaccination and
the injury; and (2) a proximate temporal relationship
between vaccination and injury, Althen v. Sec’y of Health
& Human Servs., 418 F.3d 1274, 1278 (Fed. Cir. 2005),
the special master concluded that both petitioners had
failed to demonstrate that the hepatitis B vaccine was the
cause in fact of their injuries. Id. at 18; Special Master
Porter Op. at *21.

    Although he had already concluded that Ms. Porter
was not entitled to compensation because she had not
established causation in fact, the special master also
addressed an independent and wholly distinct reason for

   2    The special master’s opinions in Porter and Rotoli
substantially overlap. For simplicity, we cite only to the
Porter opinion in these instances.
9                                              PORTER   v. HHS


denying her claim. Id. at *21-22. The government argued
that an alternative cause, i.e., the drug minocycline,
induced Ms. Porter’s AIH. The special master found that
a preponderance of the evidence established that it was
more likely than not that the minocycline caused Ms.
Porter’s AIH.

                             III

    Petitioners sought review of the special master’s deci-
sions in their respective cases in the Claims Court. The
Claims Court set aside the special master’s factual find-
ings, reasoning that this court’s decision in Andreu re-
quired that result. Rotoli v. Sec’y of Health & Human
Servs., 89 Fed. Cl. 71, 80-82 (2009). The Claims Court
read Andreu to mean that a special master may not use
credibility determinations to reject a petitioner’s theory of
causation. Id. at 82. The Claims Court, based on that
understanding of our case law, set aside the special
master’s factual findings on the ground that the special
master had “erroneously used his assessment of Dr.
Bellanti’s credibility . . . as a basis for rejecting Dr. Bel-
lanti’s expert testimony regarding causation.” Id. at 81-
82. Indicating that the special master’s credibility deter-
minations “permeated his analysis of the petitioners’
claims,” the Claims Court set aside the entirety of the
special master’s factual findings, rather than specific
adverse credibility findings. Id. at 82.

    Having discarded all of the special master’s fact find-
ing because he made credibility assessments about Dr.
Bellanti’s testimony, the Claims Court entered its own
findings based on the record. The court credited Dr.
Bellanti’s medical theories causally connecting the hepati-
tis B vaccine to AIH and ruled that petitioners had satis-
fied their burden with respect to this element of causation
PORTER   v. HHS                                        10


in fact. Id. at 83-88. As for the timing of Ms. Rotoli’s
injuries, the Claims Court found an appropriate temporal
relationship between the vaccine and the disease, dis-
counting Dr. Koff’s opinion that Ms. Rotoli’s liver biopsy
demonstrated that her AIH predated her receipt of the
vaccine by several years. Instead, the Claims Court
credited Ms. Rotoli’s alternative theory that substantial
“fibrosis might be able to form in as little as sixteen
weeks.” Id. at 89. The Claims Court also rejected the
government’s showing that Ms. Porter’s AIH was caused
by minocycline, instead crediting Dr. Bellanti’s testimony
that minocycline was not the cause because her symptoms
did not improve after discontinuing the drug. Id. at 97-
98. The court ultimately concluded that both petitioners
were entitled to compensation.

    After further proceedings concerning damages, final
judgment was entered for petitioners and damages
awarded. These appeals followed. We have jurisdiction
pursuant to 42 U.S.C. § 300aa-12(f).

                       DISCUSSION

                            I

    We review de novo decisions of the Claims Court aris-
ing under the Vaccine Act, applying the same standard of
review as the Claims Court applied to its review of the
special master’s decision. Andreu, 569 F.3d at 1373. We
owe no deference to the Claims Court or the special
master on questions of law. Id. We uphold the special
master’s findings of fact unless they are arbitrary or
capricious. Broekelschen v. Sec’y of Health & Human
Servs., 618 F.3d 1339, 1345 (Fed. Cir. 2010). “‘Thus,
although we are reviewing as a matter of law the decision
of the Claims Court under a non-deferential standard, we
11                                            PORTER   v. HHS


are in effect reviewing the decision of the special master
under the deferential and capricious standard on factual
issues.’” Lombardi v. Sec’y of Health & Human Servs.,
656 F.3d 1343, 1350 (Fed. Cir. 2011) (quoting Lampe v.
Sec’y of Health & Human Servs., 219 F.3d 1357, 1369
(Fed. Cir. 2000)). We do not reweigh the factual evidence,
assess whether the special master correctly evaluated the
evidence, or examine the probative value of the evidence
or the credibility of the witnesses—these are all matters
within the purview of the fact finder. Broekelschen, 618
F.3d at 1349 (citing Munn v. Sec’y of Health & Human
Servs., 970 F.2d 863, 871 (Fed. Cir. 1992)). Rather, as
long as a special master’s finding of fact is “‘based on
evidence in the record that [is] not wholly implausible, we
are compelled to uphold that finding as not being arbi-
trary or capricious.’” Cedillo v. Sec’y of Health & Human
Servs., 617 F.3d 1328, 1338 (Fed. Cir. 2010) (quoting
Lampe, 219 F.3d at 1360). It is not our role to “‘second
guess the Special Master[’]s fact-intensive conclusions’
particularly in cases ‘in which the medical evidence of
causation is in dispute.’” Id. (quoting Hodges v. Sec’y of
Health & Human Servs., 9 F.3d 958, 961 (Fed. Cir. 1993)).

     A petitioner seeking compensation under the Vaccine
Act must prove by a preponderance of the evidence that
the injury at issue was caused by a vaccine. 42 U.S.C.
§§ 300aa–11(c)(1); –13(a)(1). Causation under the Vaccine
Act can be shown in one of two ways. The first method of
proving causation involves demonstrating that the peti-
tioner sustained an injury in association with a vaccine
listed in the Vaccine Injury Table.           Id. § 300aa–
11(c)(1)(C)(i). In such cases, causation is presumed. See
Andreu, 569 F.3d at 1374. Alternatively, if the com-
plained-of injury is not listed in the Vaccine Injury Table,
the petitioner may seek compensation by proving causa-
tion in fact. Moberly v. Sec’y of Health & Human Servs.,
PORTER   v. HHS                                           12


592 F.3d 1315, 1321 (Fed. Cir. 2010); see also 42 U.S.C.
§ 300aa–11(c)(1)(C)(ii). Ms. Porter’s and Ms. Rotoli’s
petitions are based on such “off-Table” injuries. Once
causation is established, the petitioner is entitled to
compensation unless the government can show by a
preponderance of the evidence that the injury is due to
factors unrelated to the vaccine, i.e., an alternative cause.
Doe v. Sec’y of Health & Human Servs., 601 F.3d 1349,
1351 (Fed. Cir. 2010); see also 42 U.S.C. § 300aa–
13(a)(1)(B).

    When a petitioner has suffered an off-Table injury, we
apply the test for establishing causation in fact outlined
in Althen:

    [The petitioner’s] burden is to show by preponder-
    ant evidence that the vaccination brought about
    her injury by providing: (1) a medical theory caus-
    ally connecting the vaccination and the injury; (2)
    a logical sequence of cause and effect showing that
    the vaccination was the reason for the injury; and
    (3) a showing of a proximate temporal relation-
    ship between vaccination and injury.

418 F.3d at 1278. “[T]he function of a special master is
not to ‘diagnose’ vaccine-related injuries, but instead to
determine ‘based on the record evidence as a whole and
the totality of the case, whether it has been shown by a
preponderance of the evidence that a vaccine caused the
[petitioner’s] injury.’” Lombardi, 656 F.3d at 1351 (quot-
ing Andreu, 569 F.3d at 1382).

    On appeal, the government contends that the Claims
Court’s threshold decision to set aside the special master’s
fact-finding in its entirety was legally erroneous because
this court has consistently recognized the special master’s
13                                            PORTER   v. HHS


authority to consider and assess the credibility of expert
witnesses in evaluating Vaccine Act claims. The govern-
ment notes that the Claims Court can issue its own fact-
finding based on the record only if the special master’s
underlying decision was arbitrary, capricious, an abuse of
discretion, or otherwise not in accordance with the law.
The government argues that the special master’s factual
findings were based on a full and amply reasoned consid-
eration of the record evidence and that no proper basis
exists for setting those findings aside under the deferen-
tial standard of review.

    Petitioners counter that the Claims Court correctly
determined that the special master had impermissibly
framed his rejection of the petitioners’ theory of causation
under the rubric of a credibility determination to immu-
nize himself from appellate review. Petitioners contend
that this constitutes legal error under Andreu, and pro-
vides a basis for the Claims Court to set aside the special
master’s findings under 42 U.S.C. § 300aa-12(e)(2)(B).
Petitioners further contend that they met their burden by
establishing the three factors required to show causation
in fact under Althen. Finally, Ms. Porter asserts that
once she established her prima facie case, the burden
shifted to the government to show that the hepatitis B
vaccine did not cause her injury. She argues that the
special master’s conclusion that minocycline caused her
injury was arbitrary and capricious.

                             II

    We first consider whether the Claims Court’s whole-
sale rejection of the special master’s fact-finding based on
his use of credibility assessments was legally erroneous.
The Claims Court cited to this court’s decision in Andreu
in support of its ruling. In that case, we explained that a
PORTER   v. HHS                                           14


special master cannot “cloak the application of an errone-
ous legal standard in the guise of a credibility determina-
tion, and thereby shield it from appellate review.”
Andreu, 569 F.3d at 1379. The Claims Court here made
no determination that the special master applied an
erroneous legal standard. Rather, the Claims Court read
Andreu to mean that it is inappropriate for a special
master to consider a petitioner’s expert’s credibility in
evaluating a petitioner’s showing of causation in fact.

    The Claims Court’s reading of Andreu is incorrect.
Indeed, this court has unambiguously explained that
special masters are expected to consider the credibility of
expert witnesses in evaluating petitions for compensation
under the Vaccine Act. Recent decisions of this court
subsequent to the Claims Court’s opinion here are in-
structive. In Moberly, we reiterated that a special master
may not cloak the application of an erroneous legal stan-
dard in the guise of a credibility determination to shield it
from appellate review. 592 F.3d at 1325 (discussing
Andreu, 569 F.3d at 1379). We went on to clarify that
this does not mean that “a special master, as the finder of
fact in a Vaccine Act case, is prohibited from making
credibility determinations regarding expert testimony.”
Id. We indicated that “[a]ssessments as to the reliability
of expert testimony often turn on credibility determina-
tions” and “[f]inders of fact are entitled—indeed, ex-
pected—to make determinations as to the reliability of
the evidence presented to them and, if appropriate, as to
the credibility of the persons presenting that evidence.”
Id. at 1326. Our discussion of the issue in Broekelschen is
equally clear. In that case, we recognized that “[e]xpert
medical testimony is often very important in Vaccine Act
cases based on off-Table injuries requiring proof of actual
causation.” Broekelschen, 618 F.3d at 1347. We again
explained that “the special master’s decision often times
15                                           PORTER   v. HHS


is based on the credibility of the experts and the relative
persuasiveness of their competing theories” and such
credibility findings “‘are virtually unchallengeable on
appeal.’” Id. (quoting Lampe, 219 F.3d at 1361). Finally,
in Doe, we upheld a special master’s factual findings as
not arbitrary and capricious “particularly in light of the
credibility findings made as to the parties’ respective
experts.” 601 F.3d at 1351. We found no basis for dis-
turbing the special master’s credibility findings as to
those experts, and again emphasized that “the special
master’s unique position to see the witnesses and hear
their testimony” makes “such credibility assessments . . .
‘virtually unreviewable on appeal.”’ Id. at 1355-56 (quot-
ing Lampe, 219 F.3d at 1362).

    In the present cases, the special master recognized
that all three experts were well-qualified, but found Dr.
Zweiman’s and Dr. Koff’s testimony to be more persuasive
than Dr. Bellanti’s in several instances when the experts’
opinions were in conflict. Rather than rejecting the
special master’s findings in their entirety, the Claims
Court should have applied the deferential arbitrary and
capricious standard of review to these findings. The
Claims Court’s blanket approach of setting aside the
factual findings without ever determining whether the
findings were arbitrary and capricious failed to accord the
deference to those findings required by the Vaccine Act
and constitutes legal error.

                            III

    Because the Claims Court did not have a proper basis
for setting aside the special master’s findings of fact and
substituting its own findings, we now turn to the special
master’s findings in order to assess whether they were
arbitrary and capricious. The special master made find-
PORTER   v. HHS                                         16


ings on each of the three elements of the Althen test for
causation in fact, finding that petitioners had failed to
carry their burden on each Althen factor. He also made
findings regarding the government’s evidence of alterna-
tive cause with respect to Ms. Porter’s AIH. To establish
a prima facie case, the petitioners bear the burden of
proving all three factors required under Althen.

                            A

    The special master found that petitioners had failed
to carry their burden of demonstrating “a medical theory
causally connecting” the hepatitis B vaccine to AIH, as
required by the Althen test, 418 F.3d at 1278. Special
Master Porter Op. at *15-16. At bottom, petitioners do not
dispute that the special master applied the proper legal
standard in evaluating their claims. Rather, their argu-
ments relate entirely to the special master’s evaluation of
the competing evidence and his ultimate findings based
on the evidence.

    At the hearing, both Dr. Zweiman and Dr. Koff testi-
fied that they were unaware of any scientific or epidemi-
ological evidence of a causal link between the hepatitis B
vaccine and AIH. Petitioners’ expert, Dr. Bellanti, prof-
fered a number of theories he claimed demonstrated that
the hepatitis B vaccine might cause AIH. The special
master examined each of these theories in great detail,
weighing all of the scientific evidence presented by both
sides.

    Dr. Bellanti’s first theory was based on a biological
mechanism known as “molecular mimicry.” Id. at *6. Dr.
Bellanti initially described molecular mimicry as a theory
he believed was “most likely to be valid.” Dr. Zweiman
presented an article that undermined the reliability of
17                                           PORTER   v. HHS


molecular mimicry as a theory causally connecting the
hepatitis B vaccine with AIH. Id. Dr. Bellanti abandoned
this theory at the hearing after being confronted with the
contrary research. He agreed that the article “doesn’t
support molecular mimicry . . . so we have to seek another
explanation.” Id.

    Dr. Bellanti’s next two theories involved “bystander
activation” and “polyclonal activation,” respectively. Id.
at *6-9. Dr. Zweiman testified that there is no evidence
that the hepatitis B vaccine induces polyclonal activation.
Id. at *9. A 2002 report of the National Academy of
Sciences’ Institute of Medicine (“IOM”) likewise concluded
that “[t]here is no evidence that the hepatitis surface
antigen (in the [hepatitis B vaccine]) is capable of by-
stander activation . . . or otherwise induces non-specific
polyclonal activation.” The special master noted that
IOM reports are favored, although not dispositive, in the
Vaccine Program. Id. at *7. Dr. Bellanti presented no
response to the IOM report, which had been filed before
he testified, nor did he present any rebuttal articles. Id.
When he was questioned about the report, he dismissed it
as “opinion,” without further articulating any reason for
his disagreement with that report. Id. Crediting Dr.
Zweiman and the IOM report, the special master found
that neither of these biological mechanisms constituted a
reliable theory for explaining how the hepatitis B vaccine
can cause AIH. Id. at *8-9.

    Dr. Bellanti’s fourth theory implicated “dysfunction in
regulatory T-cells.” Id. at *9-11. Regulatory T-cells are
responsible for suppressing immune reactions against the
body’s own tissues. Dr. Bellanti’s expert report posited
that “[s]tudies suggest that a decrease in the number of
regulatory T-cells and their ability to expand may lead to
autoimmune liver disease.” Id. at *9. In support of the T-
PORTER   v. HHS                                           18


cell dysfunction theory, Dr. Bellanti pointed to an article
by Maria Serena Longhi, et al., entitled “Impairment of
CD4+ CD25+ regulatory T-cells in autoimmune liver
disease,” 41 Journal of Hepatology 31-37 (2004) (“Longhi
article”). Id. at *10. Dr. Zweiman agreed that a problem
with regulatory T-cells may be associated with AIH, but
testified that it is unclear whether the AIH causes the
dysfunction or the dysfunction causes the AIH. He fur-
ther testified that “nobody has ever reported whether or
not hepatitis immunization induces alteration of immu-
noregulatory T-cells.” Id. at *11. Dr. Bellanti did not
dispute this assertion. Id. The special master observed
that none of the testimony linked the observation in the
Longhi article that people with AIH have a T-cell imbal-
ance with the hepatitis B vaccine. Id. In fact, he noted
that Dr. Bellanti’s own report stopped short of identifying
the vaccine as a cause of regulatory T-cell dysfunction.
When the special master specifically asked Dr. Bellanti
whether his theory was “that something in the hepatitis B
vaccine causes the T-cell regulatory deficiency,” Dr.
Bellanti responded: “That isn’t known . . . the article
simply referred to a deficiency in patients with autoim-
mune hepatitis. Whether it was the cause or the result, it
isn’t clear. . . . I would favor it being a preexisting defi-
ciency, but . . . that would be speculative.” Id. at *10. In
view of the testimony and the article, the special master
found that Dr. Bellanti “could not connect the hepatitis B
vaccine to his belief that an imbalance in T-regulatory
cells causes autoimmune hepatitis.” Id. at *11. Accord-
ingly, the special master concluded that T-cell dysfunction
does not qualify as a medical theory causally connecting
the vaccination and the injury.

   Dr. Bellanti presented two additional observations in
support of a causal link between the hepatitis B vaccine
and AIH. First, he contended that, because the hepatitis
19                                            PORTER   v. HHS


B virus itself may cause autoimmune disease, one can
assume that the hepatitis B vaccine can also cause auto-
immune disease. Id. at *12. Relying on a review article
in the New England Journal of Medicine by Dr. Edward
Krawitt, a leading researcher in AIH, the special master
rejected the underlying premise of Dr. Bellanti’s claim,
i.e., that hepatitis B virus causes AIH. Id. at *13. The
Krawitt review article concluded that autoimmune hepa-
titis had been associated with hepatitis A and hepatitis C
infections, but significantly, the article did not mention a
similar association with respect to hepatitis B infection.
Id. Dr. Bellanti offered four articles that minimally
support the proposition that the hepatitis B virus can
cause AIH. Id. Dr. Koff testified that the subject in one
of the articles actually had chronic hepatitis B, not AIH.
Id. at *12. He also testified that the subject in another
article likely had hepatitis C, not AIH. Id. The special
master found that the remaining two articles, both de-
scribing single case studies, did not contain any meaning-
ful analysis about causation. Id. at *13. The special
master found that “[a] preponderance of the direct evi-
dence regarding the hepatitis B virus contradicts an
assertion that it can cause autoimmune hepatitis.” Id. at
*14.

    Dr. Bellanti also asserted that there were “reports in
the literature” that the hepatitis B vaccine had caused a
“rechallenge event” in people with autoimmune diseases,
supporting a causal connection between the vaccine and
AIH. Id. at *15. “A rechallenge event occurs when a
patient who had an adverse reaction to a vaccine suffers
worsened symptoms after an additional injection of the
vaccine.” Capizzano v. Sec’y of Health & Human Servs.,
440 F.3d 1317, 1322 (Fed. Cir. 2006). The special master
recognized that such an event can be persuasive evidence
that a vaccine is causing an adverse reaction. Special
PORTER   v. HHS                                          20


Master Porter Op. at *15. Problematically, at the hearing,
Dr. Bellanti did not cite any specific literature about
rechallenge with the hepatitis B vaccine nor could he
explain the basis for his assertion. Id. The special mas-
ter acknowledged that experts are not required to produce
literature under Althen; however, Dr. Bellanti’s expert
report stated that there were such reports in the litera-
ture. The special master noted that “Dr. Bellanti’s inabil-
ity to prove what he wrote implicated his persuasiveness
and his veracity.” Id. at *15 n.7. The special master also
considered a 2005 study by J. Beran, et al., in the Central
European Journal of Public Health submitted by Dr.
Zweiman. Id. at *15. The study reported that the condi-
tion of people with preexisting AIH did not worsen after
receiving the hepatitis B vaccine. The special master
found that the Beran study was further evidence contrary
to Dr. Bellanti’s assertion regarding the applicability of
the rechallenge. Id.

    After carefully considering Dr. Bellanti’s numerous
theories, the special master found each to be flawed and
concluded that “none . . . presents a reliable explanation
of how the hepatitis B vaccine can cause autoimmune
hepatitis.” Id. at *5. As we have previously indicated,
“reversible error will be extremely difficult to demon-
strate” where the special master “has considered the
relevant evidence of record, drawn plausible inferences
and articulated a rational basis for the decision.” Hines v.
Sec’y of Health & Human Servs., 940 F.2d 1518, 1528
(Fed. Cir. 1991).

    The special master’s decision reveals a thorough and
careful evaluation of all of the evidence including records,
tests, reports, and medical literature, as well as the
experts’ opinions and their credibility. The special master
weighed the conflicting evidence and concluded that
21                                            PORTER   v. HHS


petitioners had not carried their burden of demonstrating
“a medical theory causally connecting” the hepatitis B
vaccine to AIH. This court does not reweigh the factual
evidence or assess whether the special master correctly
evaluated the evidence, nor does it examine the probative
value of the evidence or the credibility of the witnesses.
These are all matters within the purview of the fact
finder. Broekelschen, 618 F.3d at 1349; Lombardi, 656
F.3d at 1354. Accordingly, the special master’s determi-
nation that petitioners had failed to prove causation in
fact by a preponderance of the evidence and that neither
petitioner was entitled to compensation under the Vaccine
Act was not arbitrary, capricious, an abuse of discretion,
or otherwise not in accordance with law. 42 U.S.C.
§ 300aa12(e)(2)(B).

                             B

    Putting aside the special master’s findings implicat-
ing Dr. Bellanti’s credibility, the special master also made
findings that did not rest on the adverse credibility of Dr.
Bellanti and were separate and independent reasons for
denying petitioners’ claims. In Ms. Rotoli’s case, the
special master found that she failed to satisfy the timing
prong of Althen because her AIH predated her vaccina-
tions. Special Master Rotoli Op. at *17-18. These find-
ings did not involve Dr. Bellanti’s credibility. Rather, the
special master based these findings on Dr. Koff’s analysis
of Ms. Rotoli’s liver biopsy.

    Dr. Koff explained that Ms. Rotoli’s liver biopsy,
which was taken less than nine months after she received
her first dose of the hepatitis vaccine, showed such exten-
sive damage that she must have had a liver disease for
many years prior to the biopsy. Id. at *17. The special
master acknowledged Dr. Koff’s training and thirty years
PORTER   v. HHS                                           22


of experience treating people with liver disease. Id. at
*18. He found Dr. Koff to be “quite certain and quite
persuasive” in his testimony that such extensive fibrosis
“cannot develop in nine months.” Id. at *17. Ms. Rotoli
did not offer any expert testimony from a hepatologist to
rebut Dr. Koff’s analysis of her biopsy or his assertion
that the damage could not have occurred in the relevant
timeframe. To offset this deficiency, Ms. Rotoli offered an
article by Hans-Iko Huppertz documenting a single case
study of a subject who was diagnosed with AIH following
hepatitis A infection. Id. The subject’s liver biopsy
showed fibrosis, and Ms. Rotoli argued that this supports
that fibrosis such as hers could have developed over a
short time frame. Id. Dr. Koff provided an alternative
interpretation of the Huppertz case study. He testified
that the subject in that case study likely had AIH before
his infection with hepatitis A. According to Dr. Koff, the
AIH caused the fibrosis but was not discovered until the
hepatitis A infection. Id. In view of the evidence, the
special master’s finding that Ms. Rotoli’s AIH began
before she received the hepatitis B vaccine was not arbi-
trary and capricious.

    The special master’s finding that the government had
proven by a preponderance of the evidence that Ms.
Porter’s longtime use of minocycline was the cause of her
AIH likewise did not rest on Dr. Bellanti’s lack of credibil-
ity. Rather, the special master relied on the undisputed
fact that minocycline is known to cause AIH, Ms. Porter’s
medical records, and Dr. Koff’s testimony. Special Master
Porter Op. at *21-22. Ms. Porter’s medical records indi-
cated that “[a] dermatologist prescribed minocycline for
Ms. Porter as early as May 15, 1991,” prior to her receipt
of doses of the hepatitis B vaccine. Id. at *21. Dr. Koff
testified that Ms. Porter’s records also indicated that Ms.
Porter took minocycline “on again and off again through
23                                             PORTER   v. HHS


at least 2002.” Based on his review of Ms. Porter’s re-
cords, Dr. Koff concluded that “the natural history of
minocycline-induced autoimmune hepatitis is very much
like we are seeing in Ms. Porter,” and that minocycline
was the more likely cause of her condition. The special
master also noted that one of Ms. Porter’s treating doctors
had “discontinued her prescription of minocycline after
Ms. Porter reported that she had hepatitis.” Id. at *22.
The special master found that action to be “consistent
with a belief that the minocycline could be causing Ms.
Porter’s liver troubles.” Id.

    To rebut the government’s showing on alternative
cause, Dr. Bellanti testified that “minocycline was not
likely to be the cause of Ms. Porter’s hepatitis because her
condition did not improve when she stopped taking the
minocycline.” Id. at *21. The special master noted,
however, that the medical literature “contains more than
one example of cases in which the hepatitis continued
after the minocycline was stopped.” Id. Dr. Koff also
testified that “minocycline-induced disease does not
invariably get better when you discontinue the drug.” He
further opined that “if you keep taking [minocycline]
intermittently over years, as in the case of Ms. Porter, it’s
not going to get better.” We cannot say that the special
master’s treatment of the conflicting evidence and his
finding that Ms. Porter’s AIH was caused by minocycline
was “so clearly wrong as to be arbitrary or capricious.”
Lampe, 219 F.3d at 1367.

     In sum, we conclude that the Claims Court committed
legal error when it set aside the special master’s findings
of fact in their entirety based on its erroneous interpreta-
tion of Andreu. We further conclude that the special
master’s determination that the petitioners were not
entitled to compensation under the Vaccine Act was not
PORTER   v. HHS                                         24


arbitrary, capricious, an abuse of discretion, or otherwise
not in accordance with law.

                       CONCLUSION

    We reverse the judgment of the Claims Court and re-
mand with instructions to affirm the special master’s
determination that neither petitioner is entitled to re-
cover under the Vaccine Act.

             REVERSED AND REMANDED
  United States Court of Appeals
      for the Federal Circuit
              __________________________

                  MONA PORTER,
                  Petitioner-Appellee,
                           v.
      SECRETARY OF HEALTH AND HUMAN
                 SERVICES,
             Respondent-Appellant.
              __________________________

                      2010-5162
              __________________________

    Appeal from the United States Court of Federal
Claims in case no. 99-VV-639, Judge Nancy B. Firestone.
               __________________________

 AMANDA KNIGHT, PERSONAL REPRESENTATIVE OF
   THE ESTATE OF CLAUDIA J. ROTOLI-BARR,
                   DECEASED,
               Petitioner-Appellee,
                           v.
      SECRETARY OF HEALTH AND HUMAN
                 SERVICES,
             Respondent-Appellant.
              __________________________

                      2010-5163
              __________________________
PORTER   v. HHS                                            2


    Appeal from the United States Court of Federal
Claims in case no. 99-VV-644, Judge Nancy B. Firestone.
               __________________________

O’MALLEY, Circuit Judge, concurring-in-part, dissenting-
in-part.
    Although I believe the trial court erred in setting
aside the entirety of the special master’s findings based
solely on his misuse of “credibility” determinations, I
cannot agree with the majority’s decision to ignore com-
pletely the special master’s improper use of those deter-
minations. In several instances, the special master’s
reliance on “demeanor” and “credibility” to reject the
petitioner’s theories undoubtedly was contrary to this
court’s case law. In addition, the special master’s unusual
and relentless attacks on the expert’s truthfulness color
the remainder of the special master’s flawed analysis.
     I also cannot endorse, as the majority does, the special
master’s arbitrary findings and erroneous legal conclu-
sions with respect to Mona Porter’s claim. While our
review of special masters’ decisions in Vaccine Act cases is
deferential, it is not a rubber stamp. And our standard of
review is not a license for special masters to discount
medical literature on a whim or misapply legal standards.
As explained below, because the special master made
arbitrary and capricious findings and applied erroneous
legal standards in rejecting Ms. Porter’s claim, I would
affirm the decision of the United States Court of Federal
Claims (“Claims Court”) on that claim. Accordingly, I
must dissent from that portion of the majority’s opinion.
For the reasons stated by the majority, however, because
there are independent bases that bar Claudia Rotoli’s
claim, I agree that the decision of the Claims Court must
be reversed as to that claim.
3                                              PORTER   v. HHS


                             I.
     I start by supplementing the majority’s recitation of
the procedural history and discussion of the special mas-
ter’s unusual opinions in these five consolidated petitions.
Originally, eight petitioners, including Mona Porter and
Claudia Rotoli, 1 filed petitions alleging that the hepatitis
B vaccine caused them to suffer from autoimmune hepati-
tis (“AIH”). 2 All eight claims were assigned to the same
special master. Ms. Porter and Ms. Rotoli, along with
several other petitioners, relied on the opinion of the same
expert, Dr. Joseph A. Bellanti, to support their claims.
    Dr. Bellanti is an immunologist whose qualifications
and credentials have not been challenged, and whose
expert opinion has been accepted by special masters in
other Vaccine Act cases. See Keenan v. Sec’y of Health &
Human Servs., No. 99-561V, 2007 WL 1231592 (Fed. Cl.
Apr. 5, 2007); Bowes v. Sec’y of Health & Human Servs.,
01-481V, 2006 WL 2849816, at *4 (Fed. Cl. Sept. 8, 2006)
(finding Dr. Bellanti persuasive in part because “Dr.
Bellanti is a physician with excellent academic creden-
tials and experience in the medical specialities [sic] of
pediatrics and immunology.”). Indeed, one special master
familiar with Dr. Bellanti from several prior cases de-

    1    Ms. Rotoli passed away on November 11, 2009, at
the age of 40, following the Claims Court’s decision in this
case. Her daughter, Amanda Knight, was appointed as
the personal representative of Ms. Rotoli’s estate, but we
refer to Ms. Rotoli as the petitioner for continuity and
clarity.
     2   AIH is a chronic liver disease in which an individ-
ual’s immune system attacks the individual’s liver as if it
is a foreign tissue. See Rotoli v. Sec’y of Health & Human
Servs., 89 Fed. Cl. 71, 76 n.2 (2009) (citing Michael P.
Manns & Arndt Vogel, Autoimmune Hepatitis, From
Mechanisms to Therapy, 43 Hepatology No. 2, Suppl. 1 S
132 (2006)).
PORTER   v. HHS                                          4


scribed him, and his counterpart, as being “as well-versed
in their fields as any two experts one could hope to ob-
tain.” Keenan, 2007 WL 1231592, at *3. That special
master found it “worth noting that the Court received Dr.
Bellanti's testimony with credibility.” Id. at *10.
    Of the eight original cases below, three settled before
the special master’s joint hearings, two for $100,000 and
one for $120,000. See Zaskoda v. Sec’y of Health & Hu-
man Servs., No. 05-241V (Fed. Cl. May 29, 2007); Wadie v.
Sec’y of Health & Human Servs., No. 99-493V (Fed. Cl.
Jan. 18, 2008); Kay v. Sec’y of Health & Human Servs.,
01-476V (Fed. Cl. Jan. 18, 2008). One of the petitioners
whose case settled, Jeffrey Zaskoda, relied on Dr. Bel-
lanti’s opinion to support his claim.
    The remaining five cases were consolidated for pur-
poses of trial before the special master. Following joint
hearings, the special master denied all of the petitions—
including Ms. Porter’s and Ms. Rotoli’s—finding that the
petitioners failed to establish by a preponderance of the
evidence that their AIH was caused by the hepatitis B
vaccine. See Porter v. Sec’y of Health & Human Servs.,
No. 99-639V, 2008 WL 4483740 (Fed. Cl. Oct. 2, 2008)
(“Special Master Porter Op.”); Rotoli v. Sec’y of Health &
Human Servs., No. 99-644V, 2008 WL 4483739 (Fed. Cl.
Oct. 2, 2008) (“Special Master Rotoli Op.”). With respect
to Ms. Porter, the special master also found that the
government met its burden of showing that Ms. Porter’s
AIH was caused by an alternate cause, namely the acne
drug minocycline. Special Master Porter Op. at *21.
    Although the majority makes no mention of this point,
the special master’s opinions in these cases are remark-
able for the sheer number of references to credibility,
demeanor, and veracity. For example, in referring to Dr.
Bellanti in his Porter decision, the special master used
5                                              PORTER   v. HHS


terms relating to credibility a total of 31 times throughout
his 36-page opinion, including the words “credibility” or
“credible” a combined 17 times, the word “demeanor”
eight times, and the words “veracity” and “truthfulness” a
combined six times. The following passages are illustra-
tive: “[t]his evasive answer decreased Dr. Bellanti's
credibility,” id. at *15; “[t]his evasive answer decreased
Dr. Bellanti’s credibility and calls into question the truth-
fulness of Dr. Bellanti’s report,” id. at *24; “this lack of
forthrightness lessens Dr. Bellanti's credibility.” id. at
*28; “Dr. Bellanti’s demeanor during his testimony
strongly reinforces the doubts about Dr. Bellanti's verac-
ity,” id. at *29; “[a] consideration of Dr. Bellanti’s report,
his testimony, and his demeanor while testifying raises
significant concerns not just about Dr. Bellanti's persua-
siveness but also his truthfulness,” id. at *30. 3 In his
Rotoli decision, the special master found that “Dr. Bel-
lanti lacked credibility about when the autoimmune
hepatitis began,” and that “his demeanor when he testi-
fied suggested, at a minimum, that he lacked confidence
in his statement” or “[a]t worst, his demeanor suggested
that he was not truthful.” Special Master Rotoli Op., at
*17.
    Many of the special master’s comments appear in a
special nine page section of the opinion entitled “Addi-
tional Comments Regarding Dr. Bellanti,” which he
devoted exclusively to attacking Dr. Bellanti’s prepared-
ness and veracity. In addition to calling Dr. Bellanti’s
expert report “misleading and not accurate,” the special

    3   Like the majority, unless otherwise noted, I cite
only to the Porter opinion when referring to issues that
overlap between the special master’s two decisions in
these cases. Any cite to the Joint Appendix likewise
refers to the appendix submitted in connection with that
appeal.
PORTER   v. HHS                                          6


master included a subsection about “Dr. Bellanti’s De-
meanor,” in which he identified ten instances during the
hearings in which Dr. Bellanti “appear[ed] uncomfort-
able,” “appear[ed] unsettled,” “appear[ed] unfamiliar,”
“lack[ed] confidence,” or was “being evasive.” Id. at *28-
30. Based on this, the special master drew what he
believed was a “reasonable” inference that Dr. Bellanti
“was aware that his opinion was flawed, yet he chose to
provide it anyway.” Id. at *30.
    This section of the special master’s opinion concludes
with the following:
   Here, so many questions about the basis for Dr.
   Bellanti's statements, contained in either his re-
   port or his testimony, have led to a question about
   Dr. Bellanti's veracity. As a professor and pub-
   lished author, Dr. Bellanti should appreciate the
   need for some evidence to substantiate his theo-
   ries. Dr. Bellanti failed to present any evidence
   that was credible and persuasive to support his
   statements and opinions. Consequently, Dr. Bel-
   lanti's opinion, as a whole, lacks any persuasive-
   ness.
Id. (emphasis added). Notably, although there is no
reason for a special master to enunciate the standard
under which his own decision will be reviewed, the special
master in this case announced that “[a] decision about the
persuasiveness of an expert is virtually not reviewable on
appeal.” Id. at *3 (citing Bradley v. Sec'y of Health &
Human Servs., 991 F.2d 1570, 1575 (Fed. Cir. 1993);
Sword v. Sec'y of Health & Human Servs., 44 Fed. Cl.
183, 188 (1999)).
    The special master’s pronouncement, however, did not
hold true upon motion for review of his decisions in the
Claims Court. In a combined opinion addressing all five
7                                             PORTER   v. HHS


cases, the Claims Court reversed the special master as to
three of the decisions after finding that his credibility
determinations ran afoul of this court’s decision in Andreu
v. Sec’y of Health & Human Servs., 569 F.3d 1367 (Fed.
Cir. 2009). See Rotoli v. Sec’y of Health & Human Servs.,
89 Fed. Cl. 71, 80-82 (2009). Specifically, the Claims
Court found that, “[j]ust as the special master did in
Andreu, the special master in these cases erroneously
‘cloaked’ much of his rejection of petitioners’ theory of
causation under the rubric of a ‘credibility’ determination
regarding [Dr. Bellanti].” Id. at 80 (citation and some
internal quotation marks omitted). In so finding, the
court relied on our decision in Andreu in which we stated
that credibility determinations are used “to assess the
candor of a fact witness, not to evaluate whether an
expert witnesses’ medical theory is supported by the
weight of epidemiological evidence.” Id. (quoting Andreu,
569 F.3d at 1379).
    The Claims Court went on to set aside all of the spe-
cial master’s findings and enter its own findings of fact
and conclusions of law pursuant to 42 U.S.C. § 300aa-
12(e)(2)(B). Id. at 82. 4 In a thorough analysis, the Claims


    4    This is not the only time the Claims Court has set
aside the findings of or rebuked this particular special
master. See e.g., Campbell v. Sec’y of Health & Human
Servs., 90 Fed. Cl. 369, 383-84 (2009) (“Despite the special
master’s attempt to insulate his decision from review by
the incantation of magic words, the court finds that he
erroneously relied on an assessment of Dr. Brawer’s
credibility as a basis for rejecting Dr. Brawer’s testimony
and concluding that Ms. Campbell had not met her bur-
den to establish causation in fact.”); Dobrydnev v. Sec’y of
Health & Human Servs., 98 Fed. Cl. 190, 208 (2011)
(reversing the special master and noting, among other
criticisms, that “[e]ither the Special Master did not care-
fully review the record or purposefully neglected to dis-
PORTER   v. HHS                                          8


Court found in favor of three of the petitioners, including
Ms. Porter and Ms. Rotoli, and for the government with
respect to the other two petitioners. Id. at 102.
    The government appealed the Claims Court’s decision
awarding compensation to the three petitioners. With
respect to Ms. Porter’s and Ms. Rotoli’s cases, the gov-
ernment argues that the Claims Court erred because it
incorrectly believed that the special master was prohib-
ited from assessing the credibility of an expert witness.
The government goes on to argue that, even if the special
master made improper credibility determinations, any
such error was harmless because the special master’s
decisions rested on independent grounds unrelated to
credibility. The majority agrees on both points and,
therefore, reverses the judgment of the Claims Court and
remands this matter with instructions to affirm the
special master’s determinations.
     With due respect to the majority, I cannot endorse the
decision of the special master in Ms. Porter’s case. For
the reasons explained below, I believe the majority gives
our recent case law regarding credibility determinations
an unduly broad reading, and then errs in overlooking the
many places in which the special master improperly
considered demeanor or credibility, made arbitrary and
capricious findings, or applied an improper legal stan-
dard. With respect to Ms. Porter’s claim, these errors
warrant overturning the special master’s decision even
under our generous standard of review. Accordingly, I
would affirm the Claims Court’s decision as to Ms. Por-
ter’s claim.




cuss highly relevant evidence from [the petitioner’s]
primary treating physician.”).
9                                            PORTER   v. HHS


                            II.
     The majority first determines that the Claims Court
incorrectly read Andreu to mean that a special master is
prohibited from making any credibility determinations in
its causation analysis. It is debatable whether the Claims
Court interpreted Andreu as creating such an absolute
principle, or whether it merely believed that the credibil-
ity determinations in this case were improper because
they were used in an attempt to mask the special master’s
personal preferences.      Even accepting the majority’s
characterization, the Claims Court’s reading of Andreu is
understandable, given that we unambiguously stated in
that decision that “[a] trial court makes a credibility
determination in order to assess the candor of a fact
witness, not to evaluate whether an expert witness’ medi-
cal theory is supported by the weight of epidemiological
evidence.” Andreu, 569 F.3d at 1379 (emphasis added)
(citing Lampe v. Sec’y of Health & Human Servs., 219
F.3d 1357, 1373-74 (Fed. Cir. 2010) (Plager, J., dissent-
ing)).
     The Claims Court in this case, of course, did not have
the benefit our subsequent decision in Moberly v. Secre-
tary of Health and Human Services, 592 F.3d 1315, at
1325-26 (Fed. Cir. 2010). In Moberly, we clarified Andreu
and explained that special masters must make determi-
nations about the reliability of evidence, including expert
testimony, which “often turn on credibility determina-
tions, particularly where . . . there is little supporting
evidence for the expert’s opinion.” Id. at 1326. We also
explained that “[f]inders of fact are entitled—indeed,
expected—to make determinations as to the reliability of
the evidence presented to them and, if appropriate, as to
the credibility of the persons presenting that evidence.”
Id. (emphasis added).
PORTER   v. HHS                                          10


    Based on its reading of Moberly, as well as statements
in two other cases in which we have endorsed the concept
of a special master making credibility determinations, the
majority finds that the Claims Court erred in setting
aside the special master’s findings. Majority Slip. Op. 14-
15 (citing Broekelschen v. Sec’y of Health & Human
Servs., 618 F.3d 1339, 1347 (Fed. Cir. 2010); Doe v. Sec’y
of Health & Human Servs., 601 F.3d 1349, 1351 (Fed. Cir.
2010)). The majority draws from these cases that “this
court has unambiguously explained that special masters
are expected to consider the credibility of expert witnesses
in evaluating petitions for compensation under the Vac-
cine Act.” Majority Slip Op. 14.
     I disagree with the majority’s characterization of our
case law for two reasons. First, the explicit statement in
Andreu that credibility determinations are more appro-
priate for fact witnesses than for experts must retain
some vitality. The decision in Moberly was by a three-
judge panel, not by the court sitting en banc, and, as a
procedural matter, could not have discarded that princi-
ple. 5 Second, the majority in this case overstates the
holding of Moberly by saying that “special masters are
expected to consider the credibility of expert witnesses” in
Vaccine Act cases. Majority Slip Op. 14 (emphasis
added). That is not what Moberly says. Rather, the panel
in Moberly explained that special masters are expected to
consider reliability, which often turns on credibility,

   5    To the extent that Moberly conflicts with Andreu,
the holding of the earlier panel decision would control.
See e.g., Johnston v. IVAC Corp., 885 F.2d 1574, 1579
(Fed. Cir. 1989) (“Where conflicting statements . . . appear
in our precedent, the panel is obligated to review the
cases and reconcile or explain the statements, if possible.
If not reconcilable and if not merely conflicting dicta, the
panel is obligated to follow the earlier case law which is
the binding precedent”).
11                                           PORTER   v. HHS


particularly where there is a dearth of evidence support-
ing the expert’s opinion. Moberly, 592 F.3d at 1326.
Thus, as we stated in Moberly, credibility can be consid-
ered “if appropriate.” Id. In other words, the majority
takes our statements that credibility assessments of
experts are permissible in Vaccine Act cases and inter-
prets them to mean that credibility assessments are
expected. That is not the law, and it invites, or at least
tolerates, the very mischief that occurred in these cases.
     Indeed, our post-Moberly decisions demonstrate that
the majority’s interpretation is erroneous. In Broekel-
schein, we expressly stated that, “[i]n general, when two
expert witnesses, both highly qualified, dispute an issue
of medical fact with supporting and contradictory evi-
dence, it is immaterial whether one witness makes a better
appearance on the stand.” 618 F.3d at 1349 (emphasis
added). In that case, the majority excused the error of the
special master (who was the same special master as in the
present cases), finding that it was harmless even
“[t]hough the special master may have improperly consid-
ered Dr. Greenberg’s demeanor.” Id. Here, there is no
dispute that Dr. Bellanti was well-qualified, yet the
special master nonetheless made extensive findings about
his demeanor and body language. Special Master Porter
Op. at *29-30. He even went so far as to draw what he
called a “reasonable inference” based on Dr. Bellanti’s
demeanor that Dr. Bellanti “was aware that his opinion
was flawed, yet he chose to provide it anyway.” Id. at *30.
That constitutes legal error, even under our post-Moberly
case law.
    Given that the special master made such a universal
demeanor-based “inference” that Dr. Bellanti offered a
knowingly flawed opinion, it is difficult to review his
decision without the taint of this pervasive legal error,
particularly in light of his numerous other “credibility”
PORTER   v. HHS                                          12


assessments. It is not surprising, therefore, that the
Claims Court would simply discard the special master’s
findings in their entirety and render its own findings in
the first instance. While I understand the temptation to
reach that result, I agree with the majority that our case
law does not justify that blanket approach. Nonetheless,
we cannot overlook, as the majority does, the many places
in which the special master’s “demeanor” or “credibility”
assessments were improper. Considering those legal
errors, and the special master’s other arbitrary and
capricious findings identified below, application of the
proper standard of review leads to the same conclusion
the Claims Court reached. With that background, I now
turn to the merits of Ms. Porter’s claim.
                            III.
    Because Ms. Porter seeks compensation for an off-
table injury, she must prove by preponderant evidence
that the hepatitis B vaccine brought about her AIH by
providing: “(1) a medical theory causally connecting the
vaccination and the injury; (2) a logical sequence of cause
and effect showing that the vaccination was the reason for
the injury; and (3) a showing of a proximate temporal
relationship between vaccination and injury.” Althen v.
Sec’y of Health & Human Servs., 418 F.3d 1274, 1278
(Fed. Cir. 2005). A petitioner that satisfies this burden is
“entitled to recover unless the [government] shows, also
by a preponderance of evidence, that the injury was in
fact caused by factors unrelated to the vaccine.” Knudsen
v. Sec'y of Health & Human Servs., 35 F.3d 543, 547 (Fed.
Cir. 1994) (alteration in original) (citation omitted).
    In establishing causation, a petitioner’s medical or
scientific explanation need only be “legally probable, not
medically or scientifically certain.” Moberly, 592 F.3d at
1322 (quoting Knudsen, 35 F.3d at 548-49). A petitioner
13                                           PORTER   v. HHS


is not required to provide medical literature or epidemi-
ologic studies linking the vaccine to the injury, as that
would raise impermissibly the petitioner’s burden and
preclude the use of circumstantial evidence permitted
under the Vaccine Act compensation program. Andreu,
569 F.3d at 1378; Althen, 418 F.3d at 1280. Nor is a
petitioner required to demonstrate a “general acceptance
in the scientific or medical communities.” Capizzano v.
Sec’y of Health & Human Servs., 440 F.3d 1317, 1325
(Fed. Cir. 2006). “[T]he purpose of the Vaccine Act’s
preponderance standard is to allow the finding of causa-
tion in a field bereft of complete and direct proof of how
vaccines affect the human body,” even if the possible link
between the vaccine and the injury is “hitherto unproven.”
Althen, 418 F.3d at 1280. Under the vaccine compensa-
tion system created by Congress, “close calls regarding
causation are resolved in favor of injured claimants.” Id.
(citing Knudsen, 35 F.3d at 549).
    In this case, the special master based his decision as
to each of the three Althen prongs on improper credibility
determinations, arbitrary findings, or erroneous applica-
tions of law. As explained below, the petitioners demon-
strated a medical theory causally connecting the hepatitis
B vaccine to AIH, namely that, because the hepatitis B
virus itself can cause AIH, it is more likely than not that
the hepatitis B vaccine can cause AIH. Ms. Porter also
satisfied the second and third Althen prongs because tests
revealed that her liver enzyme levels spiked shortly after
receiving her third hepatitis B vaccine dose, an indication
of AIH, which the unrebutted evidence showed was a
medically appropriate timeframe for the occurrence of
such injuries. Finally, the government failed to meet its
burden of proving that Ms. Porter’s use of minocycline
more likely than not caused her AIH because Ms. Porter’s
AIH did not improve after discontinuing use of mino-
PORTER   v. HHS                                          14


cycline, a known characteristic of drug-induced hepatitis.
As explained in more detail below, the special master’s
findings as to each of these issues fail to survive even our
generous standard of review.
                            A.
    With respect to the first prong of Althen, we have
stated that it would be inconsistent with the Vaccine Act’s
compensation program “to require identification and proof
of specific biological mechanisms.” Knudsen, 35 F.3d at
549. Even a possible link between a vaccine and an injury
that has not been proven, and in which there is an ab-
sence of direct proof, is sufficient. Althen, 418 F.3d at
1280. In this case, petitioners advanced several theories
causally connecting the hepatitis B vaccine to AIH, only
one of which is necessary to satisfy this prong. At a
minimum, the evidence showed that, because the hepati-
tis B virus itself can cause AIH, it is more likely than not
that the hepatitis B vaccine can cause AIH.
     The special master rejected Dr. Bellanti’s theory be-
cause he found there was no support for the underlying
premise – i.e., that the hepatitis B virus itself can cause
AIH. In doing so, however, the special master held Dr.
Bellanti to a heightened burden on this point. In his
expert report, Dr. Bellanti stated that “infection with
hepatitis B virus is known to cause automminue hepati-
tis.” Joint Appendix (“J.A.”) 123. The special master
latched onto Dr. Bellanti’s statement that the causation
“is known” and focused more on disproving Dr. Bellanti’s
precise statement than on applying the correct legal
standard, which does not require the theory to be
“known.” Indeed, in his special “Additional Comments
Regarding Dr. Bellanti,” the special master found that,
“[a]lthough Dr. Bellanti states this fact ‘is known,’ a
preponderance of the evidence indicates that Dr. Bel-
15                                             PORTER   v. HHS


lanti's statement was in error.” Special Master Porter Op.,
at *23 (emphasis added); see also id. at *12 (noting that
lack of citations in the report “seems inconsistent with a
fact that Dr. Bellanti asserts ‘is known.’”). But it is ir-
relevant whether Dr. Bellanti is correct that the link is
“known”; the relevant inquiry is whether a preponderance
of the evidence supports this theory, whether or not it is
medically certain or generally accepted in the scientific
community. See Moberly, 592 F.3d at 1322 (quoting
Knudsen, 35 F.3d at 548-49); Capizzano, 440 F.3d at 1325.
Accordingly, to the extent the special master focused on
whether the causal connection between the hepatitis B
virus and AIH “is known” rather than on the correct legal
standard, the special master applied an impermissibly
strict burden on petitioners. 6 That error alone warrants
setting aside his findings.
     In addition to the special master’s error in holding pe-
titioners to a heightened burden, the special master’s
factual findings also are arbitrary and capricious. In
support of his assertion that the hepatitis B virus could
cause AIH, Dr. Bellanti relied on a medical textbook
entitled The Autoimmune Diseases (Noel R. Rose and Ian
R. Mackay, eds., 3d ed. 1998). The special master found
that this textbook “appears to supports [sic] Dr. Bellanti’s
assertion.” Special Master Porter Op., at *12. He also
noted that “[n]ormally, a textbook would be a reliable
basis for a statement.” Id. at *24.
    The special master, however, took the extraordinary
step of discounting unequivocal statements in a textbook

     6  Although the special master also concluded that a
preponderance of the evidence does not support that the
hepatitis B virus can cause AIH, presumably applying the
correct standard, it is difficult to separate this statement
from the special master’s otherwise improper legal bur-
den.
PORTER   v. HHS                                           16


based on the fact that the articles which the textbook cites
are dated in 1989 and 1984. 7 Even more remarkable, the
special master discounted one of the articles, which was
written in German, because he found that it involved
chronic hepatitis B, not AIH, a finding that was based on
testimony from a witness who admittedly could not even
read the article. Specifically, the special master cited the
testimony of the government’s expert, Dr. Raymond Koff,
for his finding that “[t]he patient in the German study
actually had chronic hepatitis B, not autoimmune hepati-
tis.” Id. at *12. But Dr. Koff testified about only one of
the four cases discussed in the article, and he admitted
that he reached his conclusion “without going through the
text in German.” J.A. 1005. He then stated that, “[t]he
other three I need more information about. I need a
translation.” Id. (emphasis added). 8 I can conceive of

    7    The government’s expert, Dr. Burton Zweiman,
criticized Dr. Bellanti for relying on the third edition of
this textbook instead of the fourth edition, but he failed to
introduce the fourth edition to support his point. See
Special Master Porter Op., at *12 n.6 (“[T]o the extent
that Dr. Zweiman is implying that the third edition of the
Rose and Mackay textbook is out-of-date and that the
fourth edition eliminates any mention of the hepatitis B
virus, respondent should have submitted the correspond-
ing chapter, chapter 26, from the fourth edition.”). There
is no indication that the fourth edition also did not cite
these same articles from 1989 and 1984.
     8   Portions of Dr. Koff’s testimony also reflect a gen-
eral bias against finding problems with the hepatitis B
vaccine, as he is concerned about inviting a flood of claim-
ants. See Rotoli J.A. 977 (“But what worries me the most
is if we accept this notion that hepatitis B vaccine, which
has this extraordinary safety record, can induce, cause,
aggravate, whatever, we are going to be inundated with
people who will make claims, and I think it would not be
good precedent to set.”). The special master did not
question Dr. Koff’s admitted bias when evaluating his
17                                            PORTER   v. HHS


nothing more arbitrary than rejecting medical literature,
cited in a medical textbook, based on the testimony of a
witness who did not, and could not, read the text of the
literature. Even our deferential review does not permit
such a conclusion, and I cannot agree with the majority
that this represents “a thorough and careful evaluation of
all of the evidence.” Majority Slip Op. 20.
    In addition to this textbook, which on its face sup-
ported Dr. Bellanti’s medical theory, Dr. Bellanti also
relied on two other articles that, according to the special
master, “seem to offer some modest support for his asser-
tion.” Special Master Porter Op., at *12. One article
described the case study of a 26-year old man who re-
ceived a Twinrix vaccine, which is a vaccine for both
hepatitis A and hepatitis B, that resulted in an acute
exacerbation of his pre-existing AIH. See Antal Csepregi,
et al., Acute Exacerbation of Autoimmune Hepatitis In-
duced by Twinix, 11 World J. Gastroenterol, 4114-4116
(2005) (the “Csepregi article”). The second article re-
ported a case study about a child with both AIH and
hepatitis B, which the authors said “strengthens the
possibility that hepatitis B virus may also act as a trigger
for this rare autoimmune disease [AIH].” Valerio Nobili,
et al., Co-occurrence of Chronic Hepatitis B Virus Infection
and Autoimmune Hepatitis in a Young Senegalese Girl, 18
Eur. J. Gastroenterol Hepatol., 927-29 (2006) (the “Nobili
article”).
    Although the special master found that these articles
supported Dr. Bellanti’s theory, the special master dis-
counted them because he felt they lacked a meaningful
causation analysis. He also found that, because they
involved single case studies, “ruling out a possible coinci-

testimony, apparently reserving all credibility assess-
ments for Dr. Bellanti alone.
PORTER   v. HHS                                          18


dence is impossible.” Special Master Porter Op., at *13.
In rejecting the persuasiveness of these studies, the
special master relied on the testimony of the govern-
ment’s expert, Dr. Zweiman, despite the fact that Dr.
Zweiman testified that he would require “suitable epide-
miologic evidence” before accepting the theory that the
hepatitis B vaccine can cause AIH. J.A. 586. Dr.
Zweiman’s strict standard of proof, however, is in direct
conflict with our case law. See Capizzano, 440 F.3d at
1325 (“[R]equiring . . . epidemiologic studies . . . is con-
trary to what we said in Althen.”).
    The special master then credited an article written by
a Dr. Krawitt to find against petitioners. In describing
potential causes for AIH, the article explained that the
most convincing evidence of viral infections leading to
AIH “is related to the hepatitis viruses.” See Krawitt,
Autoimmune Hepatitis, 354 N Eng. J. Med. 54-66 (2006)
(the “Krawitt article”) (emphasis added). Although the
text of the article on its face actually supports Dr. Bel-
lanti’s theory, the special master looked beyond the text to
find significance in the types of studies cited in footnotes
to support that statement, which consisted of three stud-
ies involving patients with hepatitis A or hepatitis C
viruses.
       The special master’s decision to credit the Krawitt
article over the Rose and Mackay textbook, the Csepregi
article, and the Nobili article is arbitrary and capricious.
First, the Krawitt article does not even directly address
the hepatitis B virus and, if anything, supports that
hepatitis B may be a cause because it refers generally to
“the hepatitis viruses” causing AIH. The special master
concluded that omitting hepatitis B was “intentional,” but
that conclusion is devoid of any support. Put simply,
nothing was “omitted”; rather the Krawitt article makes a
blanket statement that “the hepatitis viruses” may cause
19                                             PORTER   v. HHS


AIH, then cites three studies in a footnote at the end of
the article to support that proposition. Although these
studies involve hepatitis A and hepatitis C viruses, sug-
gesting that there was an “omission” that was “inten-
tional” reads a conclusion into the article that is simply
absent.
    The special master’s only support for his conclusion is
the testimony of the government’s expert, Dr. Koff, who
said that he spoke to Dr. Krawitt between hearing sessions
and learned in these out-of-court discussions that Dr.
Krawitt is not aware of the hepatitis B virus causing
autoimmune hepatitis. Special Master Porter Op., at *14.
Like the Claims Court, I am “deeply suspicious” of these
discussions. Rotoli, 89 Fed. Cl. at 86 n.18. If the govern-
ment had testimony from Dr. Krawitt, it should have
presented it directly rather than relying on belated out-of-
court discussions between hearing sessions. Even accept-
ing Dr. Krawitt’s statements, the fact that Dr. Krawitt, or
anyone in the field for that matter, is not aware of a
possible link between a vaccine and an injury does not
preclude a finding of causation as a matter of law. See
Althen, 418 F.3d at 1280 (allowing a finding of causation
even if the possible link between the vaccine and the
injury is “hitherto unproven”); cf. Gass v. Marriott Hotel
Servs., Inc., 558 F.3d 419, 436 (6th Cir. 2009) (Boggs, C.J.,
dissenting) (“Of course, the absence of evidence is not the
same as evidence of absence.”).
    In short, the special master discredited a medical
textbook (in part based on testimony from a witness who
could not read one of the underlying articles) and two case
studies supporting Dr. Bellanti’s theory. Instead, he
found against the petitioner based on an article that on its
face also supports Dr. Bellanti’s theory by placing great
weight on an imagined omission. Even putting aside that
the special master imposed an improper burden on peti-
PORTER   v. HHS                                          20


tioners to show what “is known” about causation, these
findings warrant reversal.
    It is important to remember that a petitioner is not
required to produce medical literature definitively linking
the vaccine to the injury. Althen, 418 F.3d at 1280.
Circumstantial evidence is both appropriate and sufficient
to demonstrate causation, including where the link be-
tween a vaccine and an injury is previously unknown and
without direct evidence supporting causation. Here, there
can be no dispute that the petitioners’ evidence meets
that standard, and the special master’s reliance on an
alternative article that is, at most, silent on the issue
exceeds the scope of his authority. This is particularly
true given that the special master dismissed Dr. Bellanti’s
opinion in its entirety through an improper assessment of
his “demeanor.”
    While I am sensitive to our standard of review – i.e.,
that this court is not to reweigh evidence or assess the
special master’s evaluation of evidence, we also are not
required to affirm a special master’s findings that are
wholly implausible. Because the special master’s findings
in this case rise to that level, I would find that the peti-
tioners have satisfied the first prong of Althen.
                            B.
     The government does not focus on the second and
third Althen prongs – which relate to the logical sequence
of cause and effect and the temporal proximity between
the vaccine and injury – in arguing that independent
grounds unrelated to credibility support the special mas-
ter’s rejection of Ms. Porter’s claim. See Appellant’s Br.
10 (“In Porter’s case, the special master primarily based
his decision on two separate and independent rationales,”
identifying Althen prong one and the alternative cause of
minocycline). Likewise, the majority’s findings in sup-
21                                           PORTER   v. HHS


port of the special master do not address these two
prongs. There is perhaps good reason for that, as the
special master’s findings on these points are perhaps the
most egregious of his decisions. Here, the special master
held Ms. Porter to an unreasonably strict burden by
requiring her to identify the specific date of the onset of
her disease, rather than a medically appropriate time-
frame, to demonstrate a relationship between her vaccine
and her injury. At the same time, the special master
himself recognized that the particulars of Ms. Porter’s
AIH made such a specific finding virtually impossible.
Based on this unreasonable standard, the special master
rejected Dr. Bellanti’s unrebutted testimony as being too
“vague.” The special master’s findings on this point must
be overturned because they are not in accordance with our
well-established law.
     The majority recites the undisputed facts showing the
strikingly close connection between the dates of Ms.
Porter’s hepatitis B vaccine doses and the date of her
blood tests showing abnormal liver function. Majority
Slip Op. 3-4. A few points are worth emphasizing. A
blood test taken the same day Ms. Porter received her
first dose of the hepatitis B vaccine, which was also two
months after she was ordered to finish off and discontinue
use of the drug minocycline, revealed that her liver func-
tions were normal. Over the next seven months, Ms.
Porter received her second and third doses of the hepatitis
B vaccine. Less than one month after receiving her third
dose of the vaccine, Ms. Porter’s blood tests showed that
her liver enzymes were elevated well beyond the normal
range. Three tests within the next 17 days all revealed
the same elevated liver enzyme levels. During that time,
Ms. Porter began feeling nauseated, itching, and turning
yellow. Later blood work and a liver biopsy both revealed
results consistent with AIH.
PORTER   v. HHS                                          22


    Dr. Bellanti testified that a reasonable time to expect
AIH to develop following a hepatitis B vaccination is
between 14 and 40 days. In his expert report, he con-
cluded that “[t]he temporal relationship between her
immunizations and the onset of symptoms is medically
appropriate . . . .” J.A. 126. The undisputed facts of this
case fully support Dr. Bellanti’s opinion. The blood test
run on the date of Ms. Porter’s first hepatitis B vaccine
showed normal liver enzyme levels, and a blood test taken
24 days after Ms. Porter’s third hepatitis B vaccine dose
revealed elevated liver enzymes. This 24-day period fits
squarely within Dr. Bellanti’s 14 to 40 day timeframe.
     There is no indication in the record that the govern-
ment challenged this testimony or offered any evidence to
contradict it, and the special master did not rely on any
contrary evidence to reject Dr. Bellanti’s theory on this
issue. Rather, the special master found that Dr. Bel-
lanti’s testimony was “vague” and faulted Dr. Bellanti
because he “simply does not know the date of onset.”
Special Master Porter Op., at *16-17. At the same time,
however, the special master acknowledged that “Dr.
Bellanti’s lack of knowledge is justified because the avail-
able information prevents anyone from establishing when
the disease began.” Id. at *17 n.8. He also found that
“determining the onset of Ms. Porter’s autoimmune hepa-
titis is difficult, if not impossible, due to the disease’s
insidious onset.” Id. at *17 (emphasis added). Nonethe-
less, the special master required Ms. Porter to establish
the specific “date” her AIH began, finding that, “[i]f she
does not establish the date her disease began, she cannot
establish the interval between a vaccination and the onset
of her disease.” Id. (emphasis added) (citing Pafford v.
Sec’y of Health & Human Servs., 451 F.3d 1352, 1358
(Fed. Cir. 2006)).
   The special master’s decision is plainly erroneous. It
23                                            PORTER   v. HHS


is well-established in our case law that the proximate
temporal relationship between the vaccine and injury
must only be within a “medically acceptable” timeframe.
See de Bazan v. Sec’y of Health & Human Servs., 539 F.3d
1347, 1352 (Fed. Cir. 2008) (stating that the standard
requires “preponderant proof that the onset of symptoms
occurred within a timeframe for which, given the medical
understanding of the disorder’s etiology, it is medically
acceptable to infer causation”); Althen, 418 F.3d at 1281
(referring to a “medically-acceptable temporal relation-
ship”). Indeed, even the case to which the special master
cites to support his conclusion refers to a “medically
acceptable time frame for the onset of the disease follow-
ing the vaccination,” not a specific date. Pafford, 451 F.3d
at 1358. By requiring Ms. Porter to identify a specific
date of onset for her disease, which the special master
acknowledged was nearly impossible, the special master
held Ms. Porter to an unreasonably high standard. Using
this improper standard to reject Dr. Bellanti’s unrebutted
testimony was erroneous, and the special master’s find-
ings on this issue should be set aside.
                            C.
    Because Ms. Porter has met all three Althen prongs,
she has established causation. Althen, 418 F.3d at 1278.
Therefore, she is entitled to compensation unless the
government can show by preponderant evidence that her
AIH is due to factors unrelated to the vaccine. Althen,
418 F.3d at 1278; see also 42 U.S.C. § 300aa-13(a)(1)(B).
The special master found that the government met its
burden of proving that Ms. Porter’s use of minocyline was
more likely than not the cause of her AIH, a finding that
the majority affirms. The special master’s finding on this
point again is erroneous, for the three independent rea-
sons discussed below, and must be reversed.
PORTER   v. HHS                                          24


First, contrary to the majority’s statement that the special
master did not make credibility determinations to reach
his conclusions on this issue, the special master expressly
and improperly assessed Dr. Bellanti’s demeanor in
evaluating the evidence about Ms. Porter’s use of mino-
cycline. Specifically, in determining that Dr. Bellanti’s
demeanor reinforced doubts about his credibility, the
special master noted that Dr. Bellanti “appear[ed] uncom-
fortable when asserting that the history of Ms. Porter’s
autoimmune hepatitis shows that the hepatitis B vaccine,
not the minocycline, caused her disease.” Special Master
Porter Op., at *30. This was one of ten findings the spe-
cial master used to draw the “reasonable inference” that
Dr. Bellanti deliberately offered a flawed opinion. Given
our statement that it is generally inappropriate to rely on
demeanor to discount the testimony of an otherwise
qualified expert, Broekelschen, 618 F.3d at 1349, the
special master’s evaluation of Dr. Bellanti’s demeanor on
this question again ran afoul of our case law.
     Second, the special master erroneously placed the
burden on Ms. Porter to disprove that minocycline was an
alternative cause, rather than placing the burden on the
government to prove its case affirmatively. Although both
sides agreed that minocycline can cause hepatitis, Dr.
Bellanti opined that minocycline did not cause Ms. Por-
ter’s AIH because her condition did not improve when she
stopped taking minocycline, a characteristic of drug-
induced hepatitis that is supported by medical literature.
The facts supporting Dr. Bellanti’s theory are undisputed.
See Special Master Porter Op., at *21 (“The factual predi-
cate for Dr. Bellanti's opinion is accurate. Ms. Porter
discontinued using minocycline. After this time, Ms.
Porter's hepatitis did not improve.”). Dr. Bellanti also
stated that only in rare cases does hepatitis persist and
become chronic after discontinuance of the drug.
25                                             PORTER   v. HHS


    In light of this evidence, it should have been the gov-
ernment’s burden to show that Ms. Porter was the rare
exception to the general rule that an individual’s condi-
tion will improve after stopping use of the drug. But the
special master flipped the burden by placing it on Ms.
Porter, faulting Dr. Bellanti for not explaining why Ms.
Porter was not one of the rare cases. See id. (“Although
Dr. Bellanti was asked to explain why Ms. Porter was not
one of these rare cases, he failed to answer the question
and provided no basis for distinguishing Ms. Porter's case
from other cases reported in the literature.”). By misplac-
ing the burden on this issue, the special master’s decision
is contrary to the statutory scheme and to our case law,
an error that the majority overlooks.
    Finally, the special master’s findings must be set
aside because he used a clear double-standard when
evaluating whether the government met its burden of
demonstrating that minocycline was the alternative cause
of Ms. Porter’s AIH. We have explained that “the stan-
dards that apply to a petitioner's proof of actual causation
in fact in off-table cases should be the same as those that
apply to the government's proof of alternative actual
causation in fact.” Knudsen, 35 F.3d at 549. Despite this
rule, the special master held Ms. Porter to a higher stan-
dard than the government on identical issues in two
specific findings.
    First, although the special master found that Dr. Bel-
lanti’s inability to identify a specific date of onset for Ms.
Porter’s injury was fatal to her claim, he excused the
government from this exacting standard. When he con-
sidered whether the government made the same impossi-
ble showing that Dr. Bellanti could not make, the special
master found summarily that, “[t]he temporal window,
despite the inherent uncertainty in stating when the
hepatitis began, is appropriate.” Special Master Porter
PORTER   v. HHS                                           26


Op., at *22. This finding is in stark contrast to his finding
on the same issue that, “[i]f [Ms. Porter] does not estab-
lish the date her disease began, she cannot establish the
interval between a vaccination and the onset of her dis-
ease.” Id. at *17. There is no evidence the government
established the date Ms. Porter’s disease began, yet that
failing was not fatal to the government’s ability to show
an alternative cause, as it was to Ms. Porter.
     In addition, the special master also considered the
significance of single case studies supporting the govern-
ment’s position while summarily discounting single case
studies that supported Dr. Bellanti’s theory of causation.
Here, the government relied on examples in the medical
literature where an individual’s hepatitis continued after
stopping use of minocycline to show that Ms. Porter’s AIH
was more likely than not cause by minocycline. The
special master found these significant, noting that “spe-
cial masters are not to discount the possibility that a
statistically rare event actually occurred in a particular
case.” Id. at *21. When Dr. Bellanti submitted articles to
support his theory that the hepatitis B virus itself can
cause AIH, however, the special master rejected these
case studies because they were single studies, such that
“ruling out a possible coincidence is impossible.” Id. at
*13. The special master, therefore, treated the govern-
ment’s examples as “statistically rare event[s] [that]
actually occurred” but found that Ms. Porter’s examples
were mere “coincidence.” Id. at *13, 21. Applying differ-
ent standards to the identical types of evidence offered by
Ms. Porter and the government without explanation is, by
definition, arbitrary and capricious. If that standard is to
mean anything short of unfettered discretion, the special
master’s decision on this point cannot stand.
27                                             PORTER   v. HHS


                             IV.
     Despite the special master’s inappropriate credibility
assessments, arbitrary findings, and application of erro-
neous legal standards in his decisions in these cases, I
agree with the majority that the special master’s rejection
of Ms. Rotoli’s claim rests on independent grounds that
are within the proper scope of his discretion. Specifically,
the special master’s finding that Ms. Rotoli failed to meet
the third Althen prong based on Ms. Rotoli’s liver biopsy
is not arbitrary and capricious. Dr. Koff testified that Ms.
Rotoli’s liver biopsy showed such an advanced stage of
fibrosis that she must have had the disease for many
years, but the biopsy was taken only eight months after
her first dose of the hepatitis B vaccine. On the other
hand, Dr. Bellanti did not opine that the fibrosis seen on
Ms. Rotoli’s liver could have developed in as little as eight
months. Based on this evidence, the special master was
within his discretion to find that “[a] preponderance of the
evidence establishes that Ms. Rotoli’s autoimmune hepa-
titis began long before she received the hepatitis B vac-
cine.” Special Master Rotoli Op., at *17. I, therefore,
agree with the majority that the Claims Court’s decision
should be reversed as to Ms. Rotoli’s claim. 9


     9    I reach this conclusion despite the special master’s
inappropriate credibility assessments of Dr. Bellanti as to
this prong. See id. (“Dr. Bellanti lacked credibility about
when the autoimmune hepatitis began . . . . Dr. Bellanti's
demeanor when he testified suggested, at a minimum,
that he lacked confidence in his statement. At worst, his
demeanor suggested that he was not truthful.”). Even
though the special master’s demeanor assessments were
in error – indeed, glaringly so – the evidence of Ms. Ro-
toli’s liver biopsy, and Dr. Koff’s testimony interpreting
that biopsy, were independently sufficient to support the
special master’s conclusion.
PORTER   v. HHS                                        28


                           V.
    For the foregoing reasons, although I agree with the
majority as to Ms. Rotoli’s claim, I would affirm the
Claims Court with respect to Ms. Porter’s claim, finding
that she is entitled to compensation. I cannot join the
majority in endorsing the special master’s pervasive
errors in his “credibility” and “demeanor” assessments,
the erroneous legal standards he applied at several steps
in his analysis, and his double standard in evaluating the
parties’ respective evidence. Accordingly, I respectfully
dissent as to that portion of the majority opinion.
