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     STATE v. LENIART—FIRST CONCURRENCE AND DISSENT

   PALMER, J., with whom McDONALD, J., joins, con-
curring in part and dissenting in part. I agree with and
join parts I and II A of the majority opinion. For the
reasons enumerated by Justice D’Auria in his concur-
ring and dissenting opinion, I disagree with part II B of
the majority opinion and conclude that the trial court’s
erroneous exclusion of the video recording of Patrick
J. Allain’s polygraph pretest interview was not harmless
error. I also disagree with part III of the majority opinion
because I believe that the defendant, George Michael
Leniart, was entitled to introduce the expert testimony
of Alexandra Natapoff, a law professor, regarding the
questionable credibility of incarcerated informants and
the risk of relying on them as witnesses in criminal pros-
ecutions.
   I reach the conclusion regarding the proffered testi-
mony of Natapoff—whose expertise on the use of jail-
house informants has not been challenged by the
state—for essentially the same reasons that are set forth
in the opinion of the Appellate Court. See State v. Leni-
art, 166 Conn. App. 142, 212–28, 140 A.3d 1026 (2016).
In particular, I agree with the Appellate Court that,
contrary to the determination of the trial court, Nata-
poff’s testimony would not have invaded the exclusive
province of the jury to assess the credibility of wit-
nesses; id., 221–24; and the subject matter of her testi-
mony was not within the ken of the average juror. Id.,
224–27. I also agree with the Appellate Court that the
trial court’s general instruction cautioning the jury
about the reliability of jailhouse informant testimony,
given in accordance with this court’s mandate in State
v. Arroyo, 292 Conn. 558, 569–71, 973 A.2d 1254 (2009),
cert. denied, 559 U.S. 911, 130 S. Ct. 1296, 175 L. Ed. 2d
1086 (2010), was an inadequate substitute for Natapoff’s
testimony. See State v. Leniart, supra, 227.
   With respect to the issue of whether Natapoff’s testi-
mony would have constituted an improper usurpation
of the jury’s role as the sole judge of witness credibility,
the Appellate Court aptly explained that, ‘‘[a]s long as
[an] expert does not directly opine about a particular
witness’ credibility or . . . testify in such a way as to
vouch indirectly for or bolster the credibility of a wit-
ness, the expert’s testimony would not invade the prov-
ince of the jury to decide credibility and may be admit-
ted.’’ Id., 223. As the Appellate Court further explained,
there was nothing in Natapoff’s testimony that
‘‘cross[ed] the line into impermissible expert testimony
regarding credibility. Natapoff, in fact, offered no testi-
mony regarding any of the particular informants in this
case, either with respect to their status as informants,
how they had obtained their information, or their poten-
tial reliability as witnesses. The defense clearly indi-
cated to the court during argument that the defendant
did not intend to ask Natapoff about the present case
and that Natapoff had no specific knowledge of the
case or the informants involved. [Rather] Natapoff’s
testimony, as proffered, was narrowly tailored to pro-
vide only general information related to informant testi-
mony and its unreliability . . . and could have aided
the jury in making its own informed and independent
assessment regarding the credibility of informants in
the present case.’’ (Citation omitted.) Id., 223–24. Con-
sequently, there was no reason to believe that Nata-
poff’s testimony would have intruded into the jury’s
exclusive domain of determining the credibility of the
state’s jailhouse informant witnesses.
   With regard to whether the information about jail-
house informants that the defendant sought to present
through Natapoff’s testimony was known to the average
juror, the Appellate Court first observed that Natapoff
testified outside the presence of the jury about ‘‘the
inherent problems associated with the use of jailhouse
informants. According to Natapoff, the manner in which
informants are used in the criminal justice system is
largely unregulated and secretive, and the public has
very little knowledge about the process. She testified
that jailhouse informants are known to fabricate infor-
mation because they are aware that they can barter
with the state for favorable treatment on the basis of
such information.
   ‘‘In particular, Natapoff stated: ‘We have evidence of
collusion between jailhouse informants in which infor-
mants cooperate in order to create stories that they
corroborate in order to persuade the government to
use that information. We know that sometimes infor-
mants and criminal offenders can be very entrepreneur-
ial about coming up with information, knowing that the
system will likely reward them in some way.’ The hope
for favorable treatment also provides a strong incentive
for informants to search out any source of information,
reliable or not, so that they can trade that information
to the authorities.
   ‘‘Natapoff also testified about studies that demon-
strate that the usual cautionary instructions given to
jurors about informant testimony generally are not
effective and that even if jurors are made aware of and
cautioned about an informant’s compensation or other
motivation to fabricate testimony, jurors are ill-
equipped to accurately evaluate an informant’s credibil-
ity and often will accept the testimony as true. One
study published by Northwestern Law School, dis-
cussed by Natapoff during her testimony, indicated that
approximately 45 percent of all the wrongful capital
convictions identified in this country were the direct
result of an informant who was lying. According to
Natapoff, informants’ stories are often difficult to cor-
roborate or to contradict, especially in cases in which
the informant’s testimony is the central evidence
against the defendant.’’ Id., 215–16.
   In addition, when the prosecutor questioned Natapoff
on cross-examination why an average juror likely would
not have sufficient knowledge about the inherent unre-
liability of jailhouse informants based on common sense
alone, Natapoff stated: ‘‘I think that a lay person on a
jury cannot know the extent of the benefits and expecta-
tions that an informant in our system would reasonably
expect to get; that a promise or an understanding made
by a police officer or prosecutor to an informant . . .
and the history of the use of informants in our jails and
prisons give informants and law enforcement knowl-
edge about benefits that a lay person couldn’t under-
stand and wouldn’t see from the outside. . . . I think
a lay person would not expect or could not be expected
to understand how much effort informants sometimes
put into coming up with information from stealing files
from other inmates to calling outside sources and ask-
ing for resources from the newspapers and media from
outside sources. They couldn’t be expected to under-
stand the culture in jails; the understanding that this
entrepreneurial approach to information is expected.
A lay person on a jury could not be expected to know
how infrequent perjury prosecutions are for informants
who turn out to be lying. In polling jurors after trials
or after cases [in which] a wrongful conviction is found,
you sometimes hear jurors say that they think that if
an informant lies, [he or she will] be prosecuted for
perjury but because that is so rare, that expectation is
misguided, although it’s a widely shared expectation, I
think, among the public.’’ (Internal quotation marks
omitted.) Id., 216–17.
  In light of Natapoff’s unchallenged testimony and
the state’s failure to present any contrary evidence or
information, by way of empirical studies or otherwise,
demonstrating that average jurors are sufficiently
knowledgeable about the use and unreliability of jail-
house informants so as to render expert testimony on
the subject unnecessary, the Appellate Court concluded
that the trial court had abused its discretion in preclud-
ing Natapoff from testifying. Id., 220–21. I agree with
this conclusion and with the Appellate Court’s reasons
for reaching it. As that court explained, although aver-
age jurors may have some limited knowledge about the
use of jailhouse informants, we cannot presume that
they are aware either of the prison culture in which
such testimony is spawned or the full extent to which
such informants are likely to benefit as a result of their
testimony. Id., 224. Jurors also are unlikely to be aware
of the efforts undertaken by jailhouse informants to
obtain their information and of the various sources of
that information. Id. Furthermore, jurors often believe
that a jailhouse informant who lies will face perjury
charges when, in fact, such charges are almost never
brought. Id., 225. Thus, even with an instruction cau-
tioning jurors to take great care in evaluating the credi-
bility of jailhouse informants, jurors are ill-equipped to
do so because they simply are unaware of the true
dangers in relying on such testimony.1 Id. Finally, jail-
house informants played a significant role in the state’s
case against the defendant; id., 221; a fact that under-
scores the importance of Natapoff’s testimony.
    It bears emphasis that both this court and the legisla-
ture have recognized the unique problems attendant to
the state’s use of jailhouse informant testimony. One
decade ago, in State v. Arroyo, supra, 292 Conn. 558,
we expressly recognized the need to educate jurors on
the inherent unreliability of jailhouse informant testi-
mony. In coming to that conclusion, we explained that,
‘‘[i]n recent years, there have been a number of high
profile cases involving wrongful convictions based on
the false testimony of jailhouse informants. . . . Sev-
eral of these cases resulted in formal investigations
that shed much needed light on the extensive use of
jailhouse informants in criminal prosecutions, an issue
that previously had been largely a closeted aspect of
the criminal justice system. . . . One such investiga-
tion . . . revealed an appalling number of instances of
perjury or other falsifications to law enforcement
. . . . The [investigation] also [revealed] that a particu-
larly clever informant realizes that a successful perfor-
mance on the witness stand is enhanced if it appears
he or she is not benefiting from the testimony. . . .
These informants wait until after [they have] testified
to request favors—a request that is generally answered.
. . . And, because the reward is not offered before the
testimony, the jury has no way to measure the infor-
mant’s motivation to fabricate testimony, as the prose-
cutor . . . is under no obligation to disclose nonex-
isting exculpatory evidence. . . . Thus, the expec-
tation of a [r]eward for testifying is a systemic reality
. . . even [when] the informant has not received an
explicit promise of a reward. In addition, several com-
mentators have pointed out that jailhouse informants
frequently have motives to testify falsely that may have
nothing to do with the expectation of receiving benefits
from the government.’’2 (Citations omitted; footnotes
omitted; internal quotation marks omitted.) Id., 567–69.
Thus, inmates have various incentives to fabricate con-
fessions by other inmates or otherwise to testify falsely,
incentives with which jurors are not likely to be familiar.
   Insofar as the informal and largely undisclosed nature
of the relationship between a typical jailhouse infor-
mant and the state is concerned, this court, in Marquez
v. Commissioner of Correction, 330 Conn. 575, 198 A.3d
562 (2019), recently explored the subject of cooperating
witnesses generally, and what we found was troubling,
to say the least.3 In particular, we addressed and
expressed concern over what we characterized as the
‘‘state’s practice of informal, off-the-record leniency
understandings with cooperating witnesses.’’ Id., 603.
We explained this practice and the serious hazards asso-
ciated with it: ‘‘These [informal, off-the-record leniency]
understandings . . . often involve a prosecutor’s sug-
gesting—although not promising—that a favorable rec-
ommendation to the sentencing judge and/or a reduc-
tion in the charges against the witness might be
forthcoming in exchange for the witness’ testimony
inculpating another defendant. . . . Often such repre-
sentations are made only to the witness’ counsel, while
the prosecutor’s communication with the witness
makes clear that there is no promise. Under such cir-
cumstances, the prosecutor may not actually know if
any representations of possible leniency have been con-
veyed by the witness’ counsel to the witness. Thereafter,
if, before the jury, the witness denies that there is any
actual ‘agreement’ or ‘deal,’ the prosecutor can accu-
rately state . . . that he does not have a reason to know
if the witness is being untruthful. Although it might very
well be accurate that no definitive promises have been
made by the state, and, even if any possible outcomes as
described to counsel might be ‘tentative,’ experienced
counsel operating in a courthouse in which he or she is
familiar with the practices of prosecutors and presiding
judges can comfortably advise the witness of the possi-
ble credit that might follow from his testimony. Thus,
these ‘hypothetical’ outcomes serve as a real incentive
to motivate a witness to testify for the state.
   ‘‘Left out of this equation, however, is the jury. . . .
These vague understandings can prevent defense coun-
sel from effectively impeaching the witness for bias,
perhaps leaving jurors with the impression . . . that
[the witness did not have] any incentive to testify favor-
ably for the state. . . . Jurors are not well versed in
the nuanced vagaries of such leniency agreements. Yet,
we rely on jurors to assess a witness’ credibility—
including a witness’ motivation to testify—while with-
holding from them critical information that would help
them assess just how motivated that witness might be.
This practice, therefore, carries with it risks that
threaten the efficient and fair administration of jus-
tice.’’4 (Citations omitted.) Id., 603–605.
   Although we indicated in Marquez that the state can
avoid the obvious problems attendant to this practice
by, inter alia, memorializing more clearly the nature of
any agreement or understanding it has with the cooper-
ating witness, we candidly acknowledged that ‘‘the
absence of an express agreement may require a defen-
dant to explore other means to reveal to the jury a
cooperating witness’ motivation to testify.’’ Id., 606. We
then stated: ‘‘For example, in an attempt to inform the
jury about a system in which promises are not explicitly
made but understandings are drawn from pretrial dis-
cussions, defendants might resort to calling expert wit-
nesses to attempt to explain to the jury just how much
leniency a cooperating witness can expect from his
testimony.’’ Id. That is precisely the kind of testimony
that Natapoff was qualified to offer in the present case.
   The problems inherent in the state’s use of jailhouse
informant testimony have become so acute that the
legislature has seen fit to weigh in on the issue during
its most recent legislative session. See Public Acts 2019,
No. 19-131 (P.A. 19-131). That legislation, among other
things, requires that prosecutors who intend to intro-
duce the testimony of a jailhouse witness disclose cer-
tain information to defense counsel, including the com-
plete criminal history of the jailhouse witness, any
pending charges, any cooperation agreement between
the state and the witness, any benefits offered or pro-
vided by the state to the witness, the substance, time
and place of any statement allegedly given by the defen-
dant to the witness, the substance, time and place of
any statement given by the witness implicating the
defendant in the charged offense, whether, at any time,
the witness recanted any testimony subject to disclo-
sure, and information concerning any other criminal
prosecution in which the jailhouse witness previously
testified or offered to testify. See P.A. 19-131, § 1. In
addition, the legislation establishes a statewide system
for recording and tracking information on the use of
jailhouse witnesses. See P.A. 19-131, § 3.
   Finally, and perhaps most significantly, under P.A.
19-131, in cases involving murder, murder with special
circumstances, felony murder, arson murder, sexual
assault in the first degree, aggravated sexual assault in
the first degree, and aggravated sexual assault of a
minor, and, upon motion of the defendant, the trial court
must conduct a hearing to decide whether a jailhouse
witness’ testimony is sufficiently reliable to be admissi-
ble. See P.A. 19-131, § 2. The legislation further provides
that, unless the prosecutor can establish by a prepon-
derance of the evidence that the witness’ testimony is
reliable, the court shall not allow the testimony to be
admitted. See P.A. 19-131, § 2. Finally, in making its
determination concerning the reliability of the witness’
testimony, the court is required to consider the factors
enumerated in P.A. 19-131, § 1, as well as the following
factors: ‘‘(1) [t]he extent to which the jailhouse [wit-
ness’] testimony is confirmed by other evidence; (2)
[t]he specificity of the testimony; (3) [t]he extent to
which the testimony contains details known only by
the perpetrator of the alleged offense; (4) [t]he extent
to which the details of the testimony could be obtained
from a source other than the defendant; and (5) [t]he
circumstances under which the jailhouse witness ini-
tially provided information supporting such testimony
to [the police] or a prosecutorial official, including
whether the jailhouse witness was responding to a lead-
ing question.’’ P.A. 19-131, § 2.
  This legislation is truly extraordinary, especially inso-
far as it requires the court to screen jailhouse informant
testimony for threshold reliability and renders the testi-
mony inadmissible unless the state can affirmatively
demonstrate the reliability of the testimony. Ordinarily,
any probative testimony is admissible unless the court
finds the witness to be incompetent by virtue of age,
infirmity, mental incapacity or the like; the opportunity
for confrontation and cross-examination is invariably
considered to be a sufficient protection against false
or misleading testimony. In creating the rarest of excep-
tions to this bedrock evidentiary principle for the testi-
mony of jailhouse informants, the legislature has mani-
fested its deep concern about the highly problematic
manner in which such testimony is used by the state.
The same considerations that prompted the legislature
to act convince me that the defendant was entitled to
the benefit of Natapoff’s expert testimony on the subject
of jailhouse informant testimony.
   I note, finally, that the majority identifies a few cases
to support its conclusion that the defendant was not
entitled to the benefit of Natapoff’s expert testimony
on the dangers inherent in the state’s use of jailhouse
informants. The majority places particular reliance,
however, on United States v. Noze, 255 F. Supp. 3d 352
(D. Conn. 2017), aff’d sub nom. United States v. Dugue,
763 Fed. Appx. 93 (2d Cir. 2019), in which the United
States District Court rejected the request of the defen-
dants in that case to adduce expert testimony concern-
ing the government’s use of ‘‘two so-called ‘cooperating
witnesses,’ i.e., alleged [coconspirators] of the defen-
dants who have pleaded guilty and who are ‘cooperat-
ing’ with the [g]overnment by testifying at trial in hopes
of receiving a sentence reduction.’’ Id., 353. I respect-
fully disagree that Noze represents persuasive prece-
dent for the majority’s holding in the present case, pri-
marily because Noze simply did not involve the pros-
ecution’s use of testimony from a jailhouse informant;
at issue, rather, was the admission of testimony from
cooperating coconspirators of the defendants in that
case. The difference between the government’s use of
cooperating coconspirator testimony in Noze and the
state’s use of jailhouse informant testimony in the pres-
ent case is as critical as it is evident: as I previously
discussed, the testimony of jailhouse informants is
readily fabricated and otherwise particularly suspect
for a number of reasons not generally apparent to
jurors. The same cannot be said of other, more tradi-
tional cooperating witnesses who, like the govern-
ment’s witnesses in Noze, have not come forward as
part of a prison culture that is largely hidden from public
view and whose testimony is not so easily concocted.
   For the foregoing reasons, I dissent from part III of
the majority opinion in which the majority determines
that the Appellate Court incorrectly concluded that the
trial court had abused its discretion in precluding the
defendant from adducing Natapoff’s expert testimony
on jailhouse informants. For the reasons set forth by
Justice D’Auria, I also dissent from part II B of the
majority opinion, in which the majority concludes that
the trial court’s erroneous exclusion of the video
recording of Allain’s polygraph pretest interview was
harmless. Because I agree with and join parts I and II
A of the majority opinion concerning the corpus delicti
rule and the propriety of the trial court’s exclusion of
the video recording of Allain’s interview, respectively,
I respectfully concur in part and dissent in part.
   1
     We previously have stated that ‘‘the trial court should instruct the jury
that the [jailhouse] informant’s testimony must be reviewed with particular
scrutiny and weighed . . . with greater care than the testimony of an ordi-
nary witness. . . . In addition, the trial court may ask the jury to consider:
the extent to which the informant’s testimony is confirmed by other evidence;
the specificity of the testimony; the extent to which the testimony contains
details known only by the perpetrator; the extent to which the details of
the testimony could be obtained from a source other than the defendant;
the informant’s criminal record; any benefits received in exchange for the
testimony; whether the informant previously has provided reliable or unrelia-
ble information; and the circumstances under which the informant initially
provided the information to the police or the prosecutor, including whether
the informant was responding to leading questions.’’ (Citations omitted;
internal quotation marks omitted.) State v. Arroyo, supra, 292 Conn. 570–71.
In the present case, the trial court complied with Arroyo by instructing the
jury that ‘‘[a]n informant may have such an interest in the outcome of this
case that his testimony may have been colored by that fact,’’ that the jury
‘‘should consider the benefits that the state has promised the informant in
exchange for his cooperation,’’ and that it ‘‘must look with particular care
at the [informant’s] testimony . . . and scrutinize it very carefully before
you accept it.’’ It is noteworthy, however, that the trial court did not instruct
the jury on any of the other considerations concerning the credibility of
jailhouse informant testimony that we identified in Arroyo.
   2
     In regard to this particular aspect of jailhouse informant testimony, in
Arroyo, we quoted the findings and observations of several commentators,
who explained, among other things, that jailhouse informants often believe
that they have nothing to lose and everything to gain by testifying for the
state because they are already incarcerated, incentives that may seem trivial
to the average person may serve as an ‘‘invitation to [commit] perjury’’ to
someone who is imprisoned, and such informants may be motivated by
‘‘emotional impetuses’’ such as ‘‘the thrill of playing detective, fear, and
survival . . . .’’ (Internal quotation marks omitted.) State v. Arroyo, supra,
292 Conn. 569 n.10.
   3
     Marquez was a habeas case involving the relationship between the state
and the petitioner’s accomplice, who had testified for the state at the petition-
er’s underlying criminal trial. See Marquez v. Commissioner of Correction,
supra, 330 Conn. 577. Everything we explained in Marquez, however, about
the nature of the relationship between the state and its cooperating witnesses
generally applies equally, if not with greater force, to the relationship
between the state and jailhouse informants. See id., 603–605.
   4
     Indeed, those risks were manifest in Marquez. At trial, the cooperating
accomplice, who was charged with felony murder and faced a mandatory
minimum prison term of twenty-five years for that offense, testified that he
expected no leniency or other consideration in exchange for his testimony,
and that he was cooperating with the state solely because it was ‘‘the right
thing to do.’’ (Internal quotation marks omitted.) Marquez v. Commissioner
of Correction, supra, 330 Conn. 581–82. Yet, ‘‘[n]otably, after [the accomplice]
testified [for the state] the prosecution chose not to pursue the felony murder
charge originally brought against him. Instead, he was sentenced to [an
effective] term of [imprisonment of nine years] . . . for . . . robbery . . .
and attempt to commit robbery . . . .’’ Id., 588.
