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SJC-11921

                     COMMONWEALTH   vs.   DERICK EPPS.



            Essex.      December 7, 2015. - July 14, 2016.

 Present:    Gants, C.J., Spina, Cordy, Botsford, Duffly, & Hines,
                                 JJ.


Assault and Battery. Child Abuse. Constitutional Law,
     Assistance of counsel. Due Process of Law, Assistance of
     counsel. Evidence, Expert opinion. Practice, Criminal,
     New trial, Assistance of counsel.



     Indictment found and returned in the Superior Court
Department on November 17, 2004.

     The case was tried before David A. Lowy, J., and a motion
for a new trial, filed on October 17, 2011, was heard by him.

     After review by the Appeals Court, the Supreme Judicial
Court granted leave to obtain further appellate review.


     David Hirsch for the defendant.
     David F. O'Sullivan, Assistant District Attorney, for the
Commonwealth.
     The following submitted briefs for amici curiae:
     Seth Miller, of Florida, Katherine H. Judson, of Wisconsin,
Adam W. Deitch & Lindsay A. Olson, of New York, & Mark W. Batten
for The Innocence Network.
     Heather Kirkwood, of Washington, & David E. Meier for David
Ayoub & others.
                                                                     2


     Matthew R. Segal, Dennis Shedd, & Chauncey B. Wood for
Committee for Public Counsel Services & others.


    GANTS, C.J.    The defendant was convicted by a Superior

Court jury of assault and battery on a child causing substantial

bodily injury, in violation of G. L. c. 265, § 13J (b).    The

prosecution contended that the defendant violently shook the two

year old child in his care based on medical testimony that the

child was diagnosed with traumatic brain injury, and scans of

her brain that showed retinal hemorrhages, subdural hematoma,

and brain swelling, the three symptoms known as "the triad"

associated with shaken baby syndrome.    The defendant, when

interviewed by the police, denied having injured the child and

reported that, hours before the child's grievous injuries became

manifest, she had fallen down the wooden stairs in her home and

had later fallen off a kitchen stool, leaving a bump on her

forehead.    The Commonwealth's medical expert offered the opinion

that injuries of the type and severity suffered by the child

could not have been caused by the short falls described by the

defendant.   The defendant called no expert to offer an opinion

to the contrary.

    In Commonwealth v. Millien, 474 Mass. 417, 418 (2016), we

noted that "[t]here is a heated debate in the medical community

as to whether a violent shaking of a baby alone can generate

enough force to cause the triad of symptoms of traumatic brain
                                                                     3


injury, and as to whether these symptoms can sometimes be caused

by a short accidental fall."   We conclude that, in the unusual

circumstances of this case, the absence of expert testimony that

the child's injuries might have been caused by her accidental

falls deprived the defendant of an available, substantial ground

of defense, and thereby created a substantial risk of a

miscarriage of justice.   We therefore reverse the judge's denial

of the defendant's motion for a new trial, vacate the

conviction, and remand the case to the Superior Court for a new

trial.1

     Background.   1.   Evidence at trial.   We summarize the

evidence presented at trial in July, 2007.     On October 9, 2004,

Sara Comeau left for work early in the morning, leaving her two

children, Veronica, age two, and Delilah, age four, in the care

of the defendant, who was her live-in boy friend.2    The two girls

were still asleep in their bedroom; the defendant was awake but

still in bed.

     The defendant told the police during two interviews on

October 10 that, after Comeau left for work, Veronica woke up

     1
       We acknowledge the amicus briefs submitted by The
Innocence Network and "concerned physicians and scientists," and
the amicus brief jointly submitted by the American Civil
Liberties Union of Massachusetts, the Committee for Public
Counsel Services, and the Massachusetts Association of Criminal
Defense Lawyers.
     2
       Sara Comeau worked as a certified nurse assistant at a
nearby nursing home.
                                                                     4


and he brought her into the bed with him.    After one to two

hours both woke up and the defendant sent Veronica downstairs by

herself while he went to use the bathroom.     He then heard

Veronica cry and found her at the bottom of the stairs; based on

what he saw and heard, it seemed that she had fallen down two or

three wooden stairs.    Veronica told him that she was all right.

Veronica then sat on a stool in the kitchen eating cereal while

the defendant played a video game.     Veronica tried to get down

from the stool by herself and fell.3    He found her on the floor,

picked her up, and saw a small red mark on the left side of her

forehead.   She cried briefly but then said that she was okay.

The defendant gave her juice and sat her on the couch, where she

then started coughing and vomited.     The defendant cleaned up the

vomit and gave her a bath.    Later, Veronica vomited again when

she was upstairs.4

     The defendant's friend, Jason Fletcher, arrived later that

morning.    When he arrived, the defendant told Fletcher that

Veronica had fallen off the stool and Fletcher saw "a bump"


     3
       Chemist Cailin Lally of the State police crime laboratory
measured the stool and determined that it was thirty inches
tall. Lally also performed an orthotolodine test, a presumptive
test for the presence of blood, on a stain found on the kitchen
floor near the stool, and the result came back positive.
     4
       Lally found a pair of children's jeans with chunky,
strong-smelling material in the hallway upstairs, and brown
chunky material with a "vomit-like" odor in the bathroom sink
upstairs.
                                                                     5


above her left eye.    The defendant and Fletcher played a

football video game downstairs while the children played

upstairs.   At around noon, Comeau returned home on her lunch

break and found the defendant in the living room with Fletcher,

sitting on the couch and playing the football video game.

Veronica was wearing pull-up underpants and a T-shirt, which was

the same T-shirt Comeau had dressed her in when Comeau put her

to bed the night before.    Comeau saw that Veronica had a red,

dime-sized mark on her forehead.    Comeau asked the defendant

what had happened, and he told her that Veronica had fallen off

the stool while she was eating breakfast.     She and the defendant

then got into an argument about neither child being fully

dressed.    Before returning to work, Comeau went upstairs and

dressed Veronica in pants and a T-shirt.     During this time,

Veronica said to her, "Mommy, I hit my head."    According to

Comeau, Veronica was not acting unusual at this time.

    After Comeau returned to work, the defendant and Fletcher

continued playing the video game downstairs while the girls were

playing upstairs.     The defendant told the police during his

interviews that, shortly after Comeau left, while he and

Fletcher were playing the video game, he heard a "boom" from

upstairs.    He initially thought that it was the children jumping

around to music, but then Delilah ran to the top of the stairs

and yelled to the defendant that Veronica had fallen.     The
                                                                        6


defendant stated that he went upstairs and found Veronica lying

on her back with "her eyes . . . almost going in the back of her

head."       He began to give her cardiopulmonary resuscitation

(CPR).       She was limp and gurgling, and her stomach expanded and

her arms flared up each time he breathed into her mouth.          Her

fingers were "like knots," and her body stiffened as if she were

having a seizure.       He panicked and yelled for Fletcher.

Fletcher came upstairs, and the defendant sent him to get Comeau

from her work.       The defendant told the police that, when his

attempts at CPR failed, he tried to put a toothbrush in her

mouth to create an airway.

        At trial, Fletcher testified that, while he was playing the

football video game downstairs with the defendant, Delilah

yelled from upstairs that Veronica had fallen.       The defendant

went upstairs while Fletcher played four downs of the football

video game.5      While the defendant was upstairs, Fletcher did not

hear any "bangs," "shouts," or "noises."       Because the defendant

had not returned, Fletcher went upstairs "to see what was going

on."6       He then saw Veronica lying unconscious on a mattress in


        5
       Jason Fletcher testified that the defendant was winning
the football video game when Delilah called for him.
        6
       There was a dispute at trial as to how much time elapsed
before Fletcher went upstairs after the defendant left; Fletcher
estimated that it was approximately two minutes. The defendant
told the police that he called for Fletcher after about thirty
seconds.
                                                                      7


the girls' bedroom and the defendant giving her mouth-to-mouth

resuscitation.   The defendant sent him to get Comeau, and he

drove to the nursing home where she worked.

    Comeau drove home immediately when she learned about

Veronica's condition and saw Veronica on the couch in the living

room with the defendant leaning over her.    Veronica had a large

lump on her head, which Comeau testified was "red and

purple/black" in color.   The defendant was attempting to

administer CPR, but Comeau screamed and told him to stop because

Veronica's stomach was raised and "she had too much air in her."

Comeau asked the defendant what had happened, and he told her

that Veronica had fallen down the stairs.     Comeau telephoned

911, and the emergency medical technicians arrived.     Fire

fighter and emergency medical technician Robert Irvin said that

Veronica was having difficulty breathing, her eyes were rolling

back, and she was sweating profusely.   According to Irvin, she

had a "bang" on her head, a black eye, a small bang on her nose,

and a red line across her chest, which, he said, looked "as if

the child had leaned up against a chair or a table."

    A neighbor, Karen Grober, saw the fire trucks and ambulance

and went outside to see what was going on.    Grober testified

that the defendant appeared "upset" and "worried."     Grober asked

him what had happened, and he said that he did not know, that he
                                                                     8


heard a big thump from upstairs, and that when he went upstairs

Veronica was on the floor, with her eyes rolling back.

    Comeau followed Veronica to Lawrence General Hospital in a

separate ambulance.   When they arrived, Comeau saw a red mark

under Veronica's ribs that had not been there when Comeau had

dressed her at lunchtime.   Comeau also saw red marks on the

inside of both of her knees.   Once the defendant arrived at the

hospital, he told Comeau that Veronica had fallen down the

stairs and had fallen off the breakfast stool, and that Delilah

had yelled at the top of the stairs that Veronica had fallen a

third time.

    At Lawrence General Hospital, medical professionals

intubated Veronica to assist her breathing and took several X-

rays, including a head computerized tomography (CT) scan.      She

was eventually "med-flighted" to Boston Children's Hospital,

where she arrived unresponsive and was displaying "posturing,"

which is an upper motor neuron sign signaling injury to the

brain.   She was placed in the pediatric intensive care unit.

The head CT scan revealed a significant amount of swelling on

the left side of Veronica's brain, as well as bleeding in the

subdural space and the subarachnoid space.   The swelling was

such that the left side of the brain was extending over and

encroaching into the right side of the brain, a condition known

in the medical community as a midline shift.   A craniotomy
                                                                     9


surgery was performed to help relieve the swelling and to help

drain some of the blood that had collected.

     Dr. Celeste Wilson, a board-certified pediatrician and

child abuse specialist, examined Veronica and found that her

left pupil was fixed and dilated, and her right pupil was very

sluggishly reactive to light.    Although she was not an

ophthalmologist, Dr. Wilson examined Veronica's eyes and found

bleeding in the back of both eyes.   An ophthalmologist

subsequently examined Veronica and found bleeding, known as

retinal hemorrhages, in both eyes, with approximately twelve

hemorrhages on the right side and five hemorrhages on the left

side.    Dr. Wilson also found bruising over Veronica's right eye,

as well as increased redness under the nostril and a bruise

under her chin.   Dr. Wilson observed additional areas of

bruising or increased redness over Veronica's mid-chest, a

bruise on her right upper back, a bruise on her left lower back,

and bruising or increased redness on her right leg at the level

of the knee on the outer side and on her left leg on the inner

side.7   Veronica was given an electroencephalogram, a test that

measures seizure activity in the brain, as well as a magnetic

resonance imaging test and repeat head CT scans.    The CT scans

revealed that a portion of Veronica's brain had infarcted, the


     7
       At trial, Dr. Celeste Wilson testified that it is not
possible to determine how long bruises have been present.
                                                                   10


medical term for the loss of function in part of the brain, as a

result of the nerve injury.   Tests did not reveal any spinal

cord damage; neck injury, aside from some swelling in the

tissues around the neck; or skull fracture.

     Dr. Wilson offered her opinion that these injuries were

"consistent with non-accidental trauma."   Specifically, she

testified that Veronica's injuries were consistent with shaken

baby syndrome,8 which she described as a clinical diagnosis based

on a constellation of findings that include subdural hemorrhage,

retinal hemorrhages, and possibly bruises or fractures.     She

explained that shaken baby syndrome "is thought to occur as a

result of significant acceleration/deceleration forces . . .

when a caretaker vigorously shakes an infant such that the head

moves back and forth."   This shaking leads to strain and tension

on the blood vessels in the brain, causing them to tear and

release blood.   When a blood vessel tears in the subdural space,

it causes bleeding in the subdural space, i.e., a subdural

hemorrhage.   The shaking forces also cause shearing and tearing


     8
       In 2009, the American Academy of Pediatrics in a policy
statement recommended that pediatricians "use the term 'abusive
head trauma' rather than a term that implies a single injury
mechanism, such as shaken baby syndrome, in their diagnosis and
medical communications." Christian, Block, and the Committee on
Child Abuse and Neglect, Abusive Head Trauma in Infants and
Children, 123 Pediatrics 1409, 1411 (2009). See Commonwealth v.
Millien, 474 Mass. 417, 423 n.7 (2016). In this opinion, we
refer to "shaken baby syndrome" (the term used at trial) and
"abusive head trauma" interchangeably.
                                                                    11


on the nerves of the brain such that they release a substance

called cytokines, which then results in brain swelling.

    Dr. Wilson testified that the normal activities of a

toddler, even one who is clumsy, would not account for the type

of injuries she described.   She also testified that blood

testing was performed and did not reveal any sign that Veronica

was suffering from a blood disease or blood disorder.    Finally,

she opined to a reasonable degree of medical certainty that a

fall of three feet could not cause Veronica's injuries and that

a fall down multiple stairs would be "extremely unlikely" to

cause them.   She stated that, apart from shaking, the

circumstances that might cause a child to sustain these types of

injuries would be a high speed motor vehicle accident or a fall

from a building or from a height of "more than [ten] feet, more

. . . on the order of [seventy] feet."   On cross-examination,

Dr. Wilson acknowledged that Dr. John Plunkett has conducted

research indicating that the same types of symptoms as occur in

shaken baby syndrome could occur from falls as low as three

feet, but she stated that such findings are not widely accepted

within the national community of pediatricians or recognized by

the American Academy of Pediatrics.   She also admitted on cross-

examination that she could not say when Veronica's injuries were

inflicted, and that it was possible for Veronica to have
                                                                     12


remained conscious for some period of time after their

infliction.

     Comeau testified that Veronica was a clumsy child and fell

down often, that she bruised easily, and that she was being

treated for a blood disorder.9    She said that Veronica and

Delilah would jump off the couch and bed, and fight with each

other.     She gave Veronica a bicycle in June, 2004, and Veronica

fell off and broke her arm several days later.     The cast did not

come off until the week before the incident.     The defendant also

described Veronica as "clumsy" and "accident prone" in his

interview to the police, and described specific instances when

Veronica had fallen, including three or four days prior when she

ran into a door and sustained a bump on her head and a slight

black eye.     Grober similarly testified that she saw the girls

outside every day and that Veronica was often falling down and

"had a lot of accidents."10

     Comeau also testified that in August or September, 2004,

the defendant told her he had slapped Veronica.     Comeau saw a

"big red welt and a handprint" between Veronica's legs and

buttocks.     During the police interviews the defendant admitted

that he and Comeau "occasionally" gave the children a "slap on


     9
          The type of blood disorder was not identified at trial.
     10
       Veronica was known as "Tonka" by her family because she
was clumsy and always banging into things and getting bruised.
                                                                  13


the butt" as a disciplinary measure.   Nika Fontaine, Comeau's

best friend and Delilah's godmother, testified that, when she

approached Comeau's home on an unknown date, she saw through the

screen door that the defendant put his hands on Veronica's arm

and shook her while Veronica was on the ground standing.

     On the evening of October 10, the defendant waived the

Miranda rights and agreed to be interviewed by Trooper Robert

LaBarge of the State police and Detective Carl Rogers of the

Haverhill police department.   He also agreed to be interviewed

later that evening by Trooper Brandon Arakelian of the State

police.   Throughout the recorded interviews the defendant denied

causing Veronica's injuries, even after his interrogators told

him that the doctors at Children's Hospital had determined that

Veronica's injuries were intentionally inflicted and that they

could not have been caused by an accidental fall.11   The

defendant also stated that he did not think Comeau had caused

the injuries.12


     11
       Trooper Brandon Arakelian of the State police told the
defendant that Arakelian knew the "who" but was asking the
defendant "to answer the why, and tell [him] what happened, and
. . . how it happened." The defendant insisted, "I am answering
the why for you." Arakelian told the defendant that he did not
think the defendant was "a mean guy who did it on purpose," but
the defendant did not waiver in his insistence that he "didn't
do anything."
     12
       On October 13, Comeau was arrested and charged with child
endangerment. She spent three days in custody before she was
released on bail. During the time she was in custody, the
                                                                   14


    As a result of the events on October 9, Veronica is

paralyzed on the right side of her body and cannot walk.

According to Comeau, Veronica's cognitive abilities are

seriously limited and she "can't comprehend."

    2.   Closing arguments.   Defense counsel informed the judge

on the first day of trial that he would not be pursuing a third-

party culprit defense and during his opening statement asked the

jury to consider "whether or not those injuries were caused by

the blows of [the defendant] or . . . by some other non-

intentional source."   But defense counsel in closing argument

abandoned the argument that Veronica's injuries were accidental

and invited the jury instead to consider whether Comeau "struck

the blow that injured Veronica" when she came home from work on

her lunch break.   He noted that Comeau was "angry and upset"

when she came home, and was alone upstairs with the children.

In contrast, he argued that the defendant was in a good mood

because he was winning in the football video game, and did not

have the state of mind necessary to injure Veronica.   As to the

timing of the blow, defense counsel noted that Dr. Wilson had

testified that "although the child suffered a very severe,



Department of Children and Families (then the Department of
Social Services) removed Delilah from her home and placed her in
foster care, and initiated a care and protection proceeding to
remove custody of both children. The prosecutor later offered
to dismiss the charges against Comeau if she testified
truthfully against the defendant; Comeau accepted the offer.
                                                                   15


traumatic shaking, . . . the child would not have been

immediately comatose."

    The prosecutor in closing argument argued that the

defendant violently shook Veronica during the time that he was

upstairs and Fletcher was downstairs.   She claimed that "two-

year olds get banged up and bruised, but they don't break like

this," arguing that "even the clumsiest two year old, even one

who's fallen off a [thirty-]inch stool or a couple of steps is

not left with parts of her brain that have literally died-off."

Rather, she said, only a fall from seventy feet or an automobile

crash where the child is ejected from the automobile could cause

these injuries.   She argued that, because there was no evidence

of a fall or crash of this magnitude, the only possible cause of

Veronica's injuries is that the defendant shook "her so

violently that it inflict[ed] those rotational forces on her

brain and in her brain."

    2.   Motion for a new trial.   The defendant, represented by

new counsel, filed a postconviction motion for a new trial under

Mass. R. Crim. P. 30 (b), as appearing in 435 Mass. 1501 (2001),

claiming first, that his trial counsel was ineffective for

failing to retain a medical expert to question whether

Veronica's injuries were caused by shaken baby syndrome and to

acknowledge the possibility that her injuries could have been

caused by an accidental short-distance fall, and second, that
                                                                   16


newly available evidence, specifically new scientific advances

on shaken baby syndrome and short falls, warranted a new trial.

    The motion judge, who was the trial judge, conducted a

three-day evidentiary hearing that concluded on May 15, 2013.

The defendant's trial counsel testified that he was aware prior

to the start of the trial that the Commonwealth was intending to

call Dr. Wilson as a witness, and that Dr. Wilson had diagnosed

Veronica with shaken baby syndrome.   Although he was aware that

CT scans and other radiological images had been taken of

Veronica's brain, he did not attempt to obtain copies of the

scans.   He conducted research into shaken baby syndrome and was

aware of the controversies around it, and contacted two experts

for assistance.   The first expert originally agreed to be

retained but then was unable to do so.   Counsel then contacted

Dr. Edward Sussman, a pathologist whose services he had used in

prior cases and in whom he had confidence.   Before counsel

retained Dr. Sussman, he learned that Dr. Sussman believed in

the validity of shaken baby syndrome as a diagnosis.   Without

viewing the CT and other radiological scans, Dr. Sussman advised

that Veronica's injuries were compatible with impact to the left

temporal lobe of the brain, and that the tearing of veins in her

brain and bilateral retinal hemorrhaging were "some evidence of

shaking."   He also advised that the multiple sites of Veronica's

injuries were not compatible with a single fall.   He said it was
                                                                   17


possible that her injuries were caused by three separate falls

on the day of the incident, but unlikely because he did not

believe that the falls were of a great enough distance.   Thus,

counsel chose not to call Dr. Sussman as a witness because

counsel "did not believe that he would be of value."

    Trial counsel also contacted other attorneys who had worked

on shaken baby cases to find out which experts they had used.

At the time of the motion hearing, he could recall that he had

spoken with only one attorney and that the attorney had

consulted with Dr. Plunkett, but had not called him to testify

at trial.   Counsel said that the attorney expressed an opinion

about Dr. Plunkett that led him to decide that Dr. Sussman was

"best."   Counsel spoke with Dr. Sussman about Dr. Plunkett's

research regarding short falls, and Dr. Sussman told him that

Dr. Plunkett was an opponent of shaken baby syndrome but that

his opinions "had been refuted in several peer review articles."

    Although trial counsel read literature critical of shaken

baby syndrome, he did not contact any of the authors of that

literature and did not seek to retain any other critics who

could be helpful as expert witnesses.   He testified that he did

not choose to call an expert because he believed, based on his

conversations with other attorneys, that doctors who questioned

the validity of shaken baby syndrome were subject to attack by

their peers, which would render them more vulnerable to cross-
                                                                  18


examination and might lead to a counter-expert being called by

the Commonwealth.   He said, however, that if he had found an

expert from out-of-State who had solid credentials and could

assist the defense, he would have "brought in" that witness to

testify.

    Regarding the strategy he ultimately did pursue, trial

counsel stated that "[his] preference was to blame [Comeau] for

the event" but "the problem that [he] had was that gap in time

between [Comeau] leaving and the child being found."     He

explained that he did not pursue a third-party culprit defense

until the closing argument because of that concern, but once Dr.

Wilson testified that Veronica could have sustained the blow and

remained conscious after Comeau had left, he had the opportunity

to pursue this defense.

    Dr. Joseph Scheller, a pediatrician and child neurologist,

testified regarding the scientific evidence that could have been

presented at trial on behalf of the defense.   First, Dr.

Scheller described what he considered the questionable

foundation of shaken baby syndrome as a valid and scientifically

supported medical diagnosis.   He explained that, although in

theory a violent shaking of a baby can cause injury, there is no

scientific evidence based on biomechanical models or animal

studies, or from video cameras or witnesses, to support the

claims made by proponents of shaken baby syndrome.   He stated,
                                                                    19


"[W]e don't really have scientific proof that [shaken baby

syndrome] happens like doctors say it happens and that [it] can

cause the injuries that are credited to it or connected with

it."    Dr. Scheller further testified that scientific studies on

shaken baby syndrome that rely on perpetrator confessions are

flawed because the confessions are unreliable.   He stated that

in the cases he has seen, the confession is one that is "either

exaggerated or coerced."13   Moreover, he stated, even if the

confession was assumed valid, he has "never once seen a

confession that explains every injury."    He explained that,

although there are video recordings that exist of people

intentionally shaking babies, the babies in those video

recordings were not harmed in the way predicted by proponents of

shaken baby syndrome, and in fact all of those babies had normal

CT scans and eye exams and "turned out fine."    Dr. Scheller also

testified that a child over three months old who is shaken is

unlikely to suffer any kind of head injury because the neck

would prevent the head from moving back and forth; however, "it




       13
       Dr. Joseph Scheller offered as an example one case in
which the child did not wake up, the parents admitted to shaking
the baby a little bit to awaken him or her, and such an
admission was reported as an admission of violent shaking. 14
Defense counsel has no duty to investigate a theoretically
possible defense that is not potentially substantial. See
Commonwealth v. Holliday, 450 Mass. 794, 807, cert. denied, 555
U.S. 947 (2008).
                                                                   20


is very easy to imagine that these youngsters will have rib

injury, skin injury and limb injury."

    Second, Dr. Scheller called into question Dr. Wilson's

diagnosis of Veronica.   Specifically, Dr. Scheller testified

that the presence and extent of Veronica's retinal hemorrhages

do not prove that she was violently shaken.     He stated that

while child abuse pediatricians and some ophthalmologists

believe one can actually shake the eyeball and cause a retinal

hemorrhage, it has never been done in a model and it has not

occurred in people known to have been shaken.    In contrast, he

stated, "we absolutely do know that you can get retinal

hemorrhages from too much pressure."    He opined, "[I]n a two-

year-old who has this type of head injury, the retinal

hemorrhage is absolutely zero evidence of any kind of shaking,

even [to] those who believe in the shaking theory[;] because

this child has so much pressure going on we have got to believe

that it was the pressure that caused the retinal hemorrhage."

He stated that he could not give an opinion to a reasonable

degree of medical certainty whether the amount and type of

retinal hemorrhages Veronica suffered would be more consistent

with abuse or falling down three stairs because "it could happen

with either" and the probability is "fifty/fifty."

    Based on his review of Veronica's medical records, Dr.

Scheller offered an opinion to a reasonable degree of medical
                                                                     21


certainty that Veronica suffered a subdural hemorrhage that

"could have easily been from an accidental injury, just as it

could have been from an inflicted injury[;] there was no way to

tell from what actually happened to Veronica that it was

accidental or inflicted."   He further stated that Veronica's

injuries could have been caused by a short distance fall of two

and one-half to three feet onto her head, and there is no way to

tell from the medical records whether the brain swelling was

more likely to have been caused by a fall or by abuse.     He

stated unequivocally, however, that, given the location of

Veronica's subdural hemorrhage, her injuries "did not come from

a shake" because it is impossible to cause a subdural hemorrhage

in only one side of the brain by shaking back and forth.     He

concluded that "without any question [Veronica] received a blow

to the left side of the head and that caused bleeding

underneath, that caused the brain to swell underneath the

bleeding and all the other problems, but that blow could have

been an accidental blow or an intentional blow.   There is just

no way to tell from looking at [the CT scan]."

    Finally, Dr. Scheller testified that shaken baby syndrome

is the subject of heated debate and widespread disagreement

among forensic pathologists, radiologists, pediatricians,

ophthalmologists, and physicists and biomedical engineers.      He

stated that, although in 2006 every pediatrician and child abuse
                                                                   22


specialist he met believed strongly that shaken baby syndrome

was a valid diagnosis, in the more recent past a "significant

minority" has recognized that the science behind shaken baby

syndrome is questionable and has instead adopted the term

"abusive head trauma" or "abusive head injury" as a more general

term for inflicted injury.   He stated that ophthalmologists

disagree on whether retinal hemorrhages prove shaken baby

syndrome; although the majority agree that retinal hemorrhages

provide some evidence in support of a shaken baby syndrome

diagnosis, a minority of ophthalmologists believe that their

presence does not point to a specific diagnosis.   Dr. Scheller

testified that, among radiologists, pathologists, and

pediatricians, the majority supporting the shaken baby syndrome

theory has shrunk.   He stated that nothing has changed in his

view or in the literature since 2007, and that he would have

come to the same conclusions about the cause of Veronica's

injuries in 2007.    Dr. Scheller stated that the only change in

the debate since 2007 has been in the increased acceptance of

the views critical of shaken baby syndrome.

    The judge denied the motion for a new trial, concluding

that trial counsel's decision not to call an expert was a

strategic judgment that was not manifestly unreasonable.     The

judge reasoned that, had counsel called a scientific expert to

testify, he would have had to "address the expert's
                                                                  23


vulnerabilities on cross-examination."   The judge found that

counsel instead "used his agile and compelling cross-examination

of Dr. Wilson to make all the essential points he needed" to

suggest the possibility that Comeau, not the defendant, had

struck the blows that injured Veronica, which was a reasonable

defense strategy.   The judge also rejected the defendant's newly

discovered evidence claim, determining that the defendant's

proffered evidence regarding shaken baby syndrome and accidental

short falls was not newly discovered because five of the seven

articles that Dr. Scheller relied upon were published before

trial and, even if it were newly discovered, the defendant's

evidence that the views of Drs. Plunkett and Scheller were "now

widely accepted is not credible."   The judge also found that the

conclusion that the medical evidence in this case was consistent

with shaken baby syndrome or abusive head trauma rather than

with multiple short falls "is supported by overwhelming medical

evidence."

    The defendant appealed, and the Appeals Court affirmed the

denial of the defendant's motion for a new trial and the

defendant's conviction in an unpublished memorandum and order

issued pursuant to its rule 1:28.   See Commonwealth v. Epps, 87

Mass. App. Ct. 1116 (2015).   The Appeals Court held that trial

counsel was not ineffective because his failure to call an

expert to testify was a strategic decision, and that decision
                                                                   24


was not "manifestly unreasonable" because, as the motion judge

reasoned, counsel made all of the essential points he needed to

make on cross-examination, and "[a]ny further exploration into

this area . . . would have undermined the defendant's ultimate

defense that someone other than the defendant, i.e., the

victim's mother, inflicted the victim's injuries."    The Appeals

Court further reasoned that counsel's decision not to call an

expert was not unreasonable because the research proffered by

the defendant at the motion for a new trial "remains in the

significant minority and subject to sizeable attack."     The court

also agreed with the judge's ruling on the newly discovered

evidence claim.   We granted the defendant's motion for further

appellate review.

    Discussion.     1.   Ineffective assistance of counsel.   To

prevail on a motion for a new trial claiming ineffective

assistance of counsel, a defendant must show that there has been

a "serious incompetency, inefficiency, or inattention of counsel

-- behavior of counsel falling measurably below that which might

be expected from an ordinary fallible lawyer," and that

counsel's poor performance "likely deprived the defendant of an

otherwise available, substantial ground of defence."

Commonwealth v. Saferian, 366 Mass. 89, 96 (1974).    Where

defense counsel makes a strategic decision not to present a

potentially substantial defense, we "ask whether the decision
                                                                  25


was manifestly unreasonable when made."   Commonwealth v. LaBrie,

473 Mass. 754, 771 (2016).   See Commonwealth v. Kolenovic, 471

Mass. 664, 674-675 (2015) ("The manifestly unreasonable test,

therefore, is essentially a search for rationality in counsel's

strategic decisions, taking into account all the circumstances

known or that should have been known to counsel in the exercise

of his duty to provide effective representation to the client

and not whether counsel could have made alternative choices").

Where that strategic decision is made after conducting a

complete investigation of the possible defense, we give

deference to defense counsel's decision and determine whether it

was manifestly unreasonable for counsel to forgo that defense

based on the information available to counsel at the relevant

time.   See Commonwealth v. Holliday, 450 Mass. 794, 807, cert.

denied, 555 U.S. 947 (2008); Commonwealth v. Candelario, 446

Mass. 847, 854-858 (2006) (counsel's failure to pursue lack of

criminal responsibility defense was not manifestly unreasonable

where "[counsel] took appropriate steps to investigate such

defenses and, after doing so, made a tactical decision that the

defenses were unlikely to succeed").   But where a strategic

decision is made to conduct something less than a complete

investigation of a potentially substantial defense, either

because defense counsel decided to forgo that defense or to

present it at trial without complete investigation, we ask
                                                                   26


whether it was manifestly unreasonable to conduct so limited an

investigation.   See Labrie, supra, quoting Commonwealth v. Lang,

473 Mass. 1, 14 (2015) (Hines, J., concurring) ("Strategic

choices made before a complete investigation are reasonable

'[only] to the extent that reasonable professional judgments

support the limitation on investigation'"); Kolenovic, supra at

670, 675 (counsel's decision to forgo further evaluation of

defendant for posttraumatic stress disorder [PTSD] after

consulting with one expert not manifestly unreasonable where

"counsel had done what was necessary to identify the defense

options based on PTSD" and "made the strategic decision that a

lack of criminal responsibility or diminished capacity defense

was unlikely to succeed and that further investigation was

unnecessary").

     Defense counsel has a professional obligation to

investigate all potentially substantial defenses.14   See

Commonwealth v. Alcide, 472 Mass. 150, 160 (2015); Commonwealth

v. Haggerty, 400 Mass. 437, 441-442 (1987).   The extent of

investigation required to explore each potential defense depends

on the strength of that defense relative to the availability and

strength of other potential defenses.   See Kolenovic, 471 Mass.


     14
       Defense counsel has no duty to investigate a
theoretically possible defense that is not potentially
substantial. See Commonwealth v. Holliday, 450 Mass. 794, 807,
cert. denied, 555 U.S. 947 (2008).
                                                                    27


at 676 ("choice between a [lack of criminal responsibility]

defense that . . . would require riding 'two horses,' and a

viable alternative defense based on the factually unassailable

intoxication defense developed by counsel" justified lack of

investigation into lack of criminal responsibility defense);

Haggerty, supra at 442 ("[f]ailure to investigate the only

defense a defendant has, if facts known to or with minimal

diligence accessible to counsel support that defense, falls

beneath the level of competency expected").   See also Lang, 473

Mass. at 15 (Hines, J., concurring); Commonwealth v. Baker, 440

Mass. 519, 529 (2003).

    Here, the defendant's trial counsel chose not to consult

with any further experts after speaking with one expert who he

knew did not question the validity of shaken baby syndrome and

who, without having viewed the medical records, offered the

opinion that Veronica's injuries could not possibly have been

caused by the accidental falls described by the defendant.     We

consider whether, in the circumstances of this case, it was

manifestly unreasonable for counsel to have decided to confer

with no other expert who might challenge the diagnosis of shaken

baby syndrome or who might challenge the opinion that Veronica's

symptoms could not possibly have been caused by the accidental

falls described by the defendant.
                                                                  28


      As became apparent at trial, defense counsel reasonably had

two alternative lines of defense:   he could argue that there was

a reasonable doubt whether the defendant caused Veronica's

injuries because of the possibility that her injuries were

caused by the accidental falls she sustained earlier that

morning -- falling down the stairs, falling off the stool, or

the cumulative effect of both falls; or that there was a

reasonable doubt whether the defendant caused Veronica's

injuries because of the possibility that Comeau intentionally

inflicted the injury.   The accidental defense had significant

evidentiary support in that the defendant had consistently

reported that Veronica fell down the stairs earlier that morning

and had fallen off the stool at breakfast.      The defendant's

report that Veronica fell from the stool was strongly

corroborated:

     The defendant told Fletcher about it when he arrived at the

      home, and Fletcher saw a "bump" over Veronica's left eye;

     When Comeau came home during her lunch break, the "bump"

      was now "dime-sized," and the defendant told her that

      Veronica had fallen from the stool; and

     Veronica herself told Comeau that she had hit her head.

Moreover, although the prosecution theory was that the defendant

violently shook Veronica after Delilah had reported that

Veronica had fallen, defense counsel reasonably could have
                                                                   29


argued that Veronica was already unconscious when Delilah called

(as the defendant reported to police) because a four year old is

unlikely to report to his or her caretaker an ordinary fall by a

two year old sibling, especially when, as here, the sibling fell

so often that she earned the nickname of "Tonka."    When Comeau

returned to her home after Veronica had become unconscious, she

reported that she saw a big "red and purple/black" lump on

Veronica's forehead, which permitted the inference that the bump

from the fall had grown into this discolored lump.

     At the time of trial, there was substantial scientific and

medical literature that recognized the possibility that

accidental short falls can cause serious head injuries in young

children of the type generally associated with shaken baby

syndrome.15   Numerous studies had also been published at the time


     15
       See, e.g., Roth, Raul, Ludes, & Willinger, Finite Element
Analysis of Impact and Shaking Inflicted to a Child, 121 Int'l
J. Legal Med. 223, 225 (2007) (based on computer simulation,
eighteen inch fall as likely to cause subdural hemorrhage as
shaking); Prange, Coats, Duhaime, & Margulies, Anthropomorphic
Simulations of Falls, Shakes, and Inflicted Impacts in Infants,
99 J. Neurosurgery 143 (2003) (shaking and minor falls produce
similar rotational responses, with falls of only twelve inches
with head impact producing accelerations in excess of those
produced during shaking); Hymel, Jenny, & Block, Intracranial
Hemorrhage and Rebleeding in Suspected Victims of Abusive Head
Trauma: Addressing the Forensic Controversies, 7 Child
Maltreatment 329 (2002) (describing two cases of serious head
trauma from accidental short falls); Jenny, Shams, Rangarajan, &
Fukuda, Development of a Biofidelic 2.5 kg Infant Dummy and Its
Application to Assessing Infant Head Trauma During Violent
Shaking, Injury Biomechanics Research, Proceedings of the
Thirtieth International Workshop, at 138 (Nov. 10, 2002) (based
                                                                 30


of trial challenging the view that shaking alone can produce the

types of injuries associated with shaken baby syndrome.16

Although these issues were hotly contested in the relevant

medical and scientific fields, see People v. Ackley, 497 Mich.

381, 385 (2015); State v. Edmunds, 308 Wis. 2d 374, 385-386

(2008), and although the experts who would support the positions

beneficial to the defense were in the minority in this debate,

there was significant medical and scientific support for these


on biomechanical experiment, maximum head center of gravity
acceleration produced by shaking less than one-third of that
produced by rolling off sofa); Plunkett, Fatal Pediatric Head
Injuries Caused by Short-Distance Falls, 22 Am. J. Forensic Med.
& Pathology 1, 7-9 (2001) (symptoms attributed to shaken baby
syndrome also found in fatal short falls); Christian, Taylor,
Hertle, & Duhaime, Retinal Hemorrhages Caused by Accidental
Household Trauma, 135 J. Pediatrics 125, 127 (1999) (reporting
three cases of infants between seven months and thirteen months
of age who had retinal hemorrhages after short falls); Hall,
Reyes, Horvat, Meller, & Stein, The Mortality of Childhood
Falls, 29 J. Trauma 1273-74 (1989) (of fatal falls by children
in Cook County, Illinois, during four-year period, forty-one per
cent were minor falls from less than three feet).
     16
       See, e.g., Bandak, Shaken Baby Syndrome: A Biomechanics
Analysis of Injury Mechanisms, 151 Forensic Sci. Int'l 71, 78
(2005) (infant shaking cannot cause serious injuries without
also resulting in neck injury); Ommaya, Goldsmith, & Thibault,
Biomechanics and Neuropathology of Adult and Pediatric Head
Injury, 16(3) Brit. J. of Neurosurgery 220, 233 (2002) (based on
standard biomechanical principles, shaken baby syndrome
hypothesis requires forces that are biomechanically improbable
and increased intracranial pressure is more likely to cause
retinal bleeding than shaking); Duhaime, Gennarelli, Thibault,
Bruce, Margulies, & Wiser, The Shaken Baby Syndrome: A
Clinical, Pathological, and Biomechanical Study, 66 J.
Neurosurgery 409, 413-414 (1987) (subjecting biomechanical model
to repetitive violent shaking demonstrated that shaking fell
below established injury thresholds).
                                                                31


minority positions.   See notes 15 and 16, supra; note 17, infra;

Millien, 474 Mass. at 435 n.16, 438 n.20.   There were also

published articles that identified the methodological

shortcomings of the research supporting the majority view on

shaken baby syndrome,17 and that highlighted the difficulties

faced by physicians in accurately diagnosing the cause of

injuries that appear to have been caused by child abuse.18


     17
       See, e.g., Vinchon, Defoort-Dhellemmes, Desurmont, &
Dhellemmes, Accidental and Nonaccidental Head Injuries in
Infants: A Prospective Study, 102 J. Neurosurgery: Pediatrics
380, 383 (2005) ("[T]he evaluation of the incidence of [retinal
hemorrhages] in child abuse remains a self-fulfilling prophecy"
because children are diagnosed as being abused "in great part
based on the presence of [retinal hemorrhage]"); Donohoe,
Evidence-Based Medicine and Shaken Baby Syndrome, 24 Am. J.
Forensic Med. & Pathology 239, 240-241 (2003) (performing review
of shaken baby syndrome literature from 1966 through 1998 and
concluding that "there existed serious data gaps, flaws of
logic, inconsistency of case definition, and a serious lack of
tests capable of discriminating [non-accidental injury] cases
from natural injuries. . . . [By 1999] the commonly held
opinion that the finding of [subdural hematoma] and [retinal
hemorrhages] in an infant was strong evidence of [shaken baby
syndrome] was unsustainable"). For example, in one study
seeking to determine whether short falls of children cause
death, after finding an unexpectedly large number of deaths
after reported short falls, the author excluded those deaths
because they assumed those reports to be false. See Chadwick,
Chin, Salerno, Landsverk, & Kitchen, Deaths from Falls in
Children: How Far Is Fatal?, 31 J. Trauma 1353, 1355 (1991).
     18
       See, e.g., Christian, Taylor, Hertle, & Duhaime, Retinal
Hemorrhages Caused by Accidental Household Trauma, 135 J.
Pediatrics 125, 127 (1999) (recognizing overlap between
accidental and abusive head injury and cautioning against
presumption of abuse when infants under one year present with
traumatic retinal hemorrhages); Sirotnak, Medical Disorders that
Mimic Abusive Head Trauma, in Abusive Head Trauma in Infants and
Children 191 (2006) (many conditions mimic abusive head trauma);
                                                                    32


     In contrast, the alternative defense that Comeau had shaken

Veronica would have required a jury to accept as a reasonable

possibility that the natural mother of Veronica, rather than the

boy friend with no biological connection to Veronica, violently

shook Veronica when she came home during her lunch break.      Apart

from the inherent difficulty in persuading a jury to accept such

a possibility, this defense suffered from two additional

challenges:   Veronica appeared normal and continued to play

after Comeau returned to work, and the defendant told the police

that he did not believe Comeau had inflicted the injury.19     In

light of these difficulties, it is not surprising that defense

counsel told the judge on the first day of trial that he did not




Barnes, Ethical Issues in Imaging Nonaccidental Injury: Child
Abuse, 13(2) Topics in Magnetic Resonance Imaging 85, 86-87, 91
(2002) (applying standard of evidence-based medicine to shaking
mechanism and concluding that no scientific basis exists
indicating force required to produce traumatic brain injury and
that many conditions mimic child abuse); Case, Graham, Handy,
Jentzen, & Monteleone, Position Paper on Fatal Abusive Head
Injuries in Infants and Young Children, 22 Am. J. Forensic Med.
& Pathology 112, 116-117 (2001) (acknowledging that retinal
hemorrhages have many nontraumatic causes, including increased
intracranial pressure, bleeding disorders, sepsis, meningitis,
and vasculopathies, and that pathogenesis of retinal hemorrhages
is not precisely understood).
     19
       Based on the information in the record, counsel made no
effort to locate a medical expert who would support the
contention that a child who suffered Veronica's injuries from a
violent shaking could have a lucid interval between the shaking
and the manifestation of symptoms.
                                                                  33


intend to offer a defense of third-party culprit,20 and that he

invited the jury in opening statement to consider whether

Veronica's injuries were accidental rather than inflicted.

     Without an expert to testify to the possibility that

Veronica's injuries might have been caused by her accidental

falls, all that trial counsel was able to do to advance the

theory of accident was to ask Dr. Wilson to acknowledge the

existence of Dr. Plunkett's findings regarding short falls,

which Dr. Wilson did and then noted that Dr. Plunkett's findings

were not widely accepted within the national community of

pediatricians and were not recognized by the American Academy of

Pediatrics (AAP).   It should have been entirely foreseeable

that, when defense counsel invites a prosecution expert to

acknowledge findings in support of a minority position in the

field of science or medicine, the expert will diminish the

significance of those findings by testifying that they are not

credited by the majority of experts in the field.   And without

an expert to testify in support of the minority position, or

vigorous cross-examination prepared with the assistance of such

an expert, there is no reason to believe that a jury will be

persuaded by a view rejected by the majority of experts in a

     20
       Defense counsel was able to resurrect the Comeau defense
in closing argument only because the prosecutor elicited
testimony from Dr. Wilson that a child after having been shaken
may not immediately be unconscious or comatose, but would not
likely be playful or eating normally.
                                                                  34


learned field.   Defense counsel apparently recognized the

futility of an accident defense without the testimony or aid of

such an expert, because, in closing argument, he effectively

abandoned the accident defense entirely, and asked the jury

simply to consider who "struck the blow."21

     Having informed the judge at the beginning of trial that he

did not plan to pursue a third-party culprit defense, defense

counsel's failure to consult with any expert other than Dr.

Sussman effectively meant that the defendant commenced trial

without any substantial defense, even though further

investigation would have supported a potentially substantial

defense of accident.22   Trial counsel testified that he would

have retained an expert to testify if he could have found one

with "solid credentials" who could assist the defense.   But when

asked if he made "any inquiries into whether any experts other

than Dr. Plunkett would be helpful as witnesses in this case,"

he answered, "No."   He also testified that he never contacted

     21
       Defense counsel in closing argument went so far as to
tell the jury, mistakenly, that the defendant during his
interviews with the police admitted that the falls he described
could not have caused Veronica's injuries.
     22
       Apart from the substantial evidence that Veronica had
suffered some head injury from her fall off the stool, the
medical evidence revealed that Veronica suffered no neck injury.
There was medical literature published at the time of trial that
concluded that neck injury would be inevitable in a shaking so
violent as to have caused the symptoms associated with shaken
baby syndrome. See note 16, supra; Millien, 474 Mass. at 433
n.15.
                                                                   35


any of the authors of the scholarly articles that questioned the

validity of shaken baby syndrome or that recognized the

possibility that short falls could cause the type of injuries

usually associated with shaken baby syndrome.   Where there was

strong, corroborated evidence that Veronica had suffered a head

injury from at least one short accidental fall, where accident

was the defense that counsel presented to the jury in opening

statement, and where this defense was tenable only with the aid

of an expert to challenge the majority views on short falls and

shaken baby syndrome, it would have been manifestly unreasonable

for counsel to have made so little effort to find and retain

such an expert if there were experts available with "solid

credentials," that is, experts who could have been found

credible by a reasonable jury, and who challenged these views.

    Whether counsel's representation in this case was

ineffective, therefore, rests on whether, at the time of trial

in July, 2007, there were credible experts available who

challenged the majority views on short falls and shaken baby

syndrome.   The record, however, is sparse on this issue; the

existence of scientific and medical studies would certainly

provide the factual basis for an expert to offer a minority

opinion on these subjects, but that does not mean that experts

were readily available in 2007 who were prepared and willing to

offer such opinions in a criminal case.   Dr. Scheller testified
                                                                   36


that credible experts were available to testify in 2007, but we

note that the judge did not find Dr. Scheller credible as an

expert himself in part because of his assertions that ventured

well beyond what was necessary to his opinion that the injuries

suffered by Veronica reasonably could have been caused by her

accidental falls.23   For reasons that will soon become clear,

however, we need not determine whether it was manifestly

unreasonable in 2007 for counsel to have failed to find a

credible expert who shared the minority view in this scientific

controversy.

     2.   Newly discovered evidence.   We now consider whether

there was newly discovered evidence in the form of new

scientific or medical findings.   Newly discovered evidence

warrants a new trial where that evidence "would probably have

been a real factor in the jury's deliberations" and where its

absence at trial "casts real doubt on the justice of the

conviction."   Commonwealth v. Cowels, 470 Mass. 607, 616, 617

(2015), quoting Commonwealth v. Grace, 397 Mass. 303, 305, 306

(1986).   Evidence is newly discovered where it was "unknown to

the defendant or his counsel and not reasonably discoverable"

through "reasonable pretrial diligence."    Grace, supra at 306.

     23
       For instance, the judge found "absurd" Dr. Scheller's
testimony that people generally do not shake babies out of
frustration and that the perception that they do is the result
of "public relation campaigns launched by child abuse
pediatricians."
                                                                 37


     Since the defendant's trial, several additional studies

have been published that provide further support for the view

that subdural hematomas, retinal hemorrhages, and other forms of

significant head injury can result from accidental short falls.24

More research has also been conducted that casts doubt on the

view that shaking alone can cause serious head injury.25   And

more articles have been published in medical and scholarly

journals questioning the diagnostic significance of the symptoms

previously thought indicative of shaken baby syndrome.26


     24
       See Barnes, Imaging of Nonaccidental Injury and the
Mimics: Issues and Controversies in the Era of Evidence-Based
Medicine, 49 Radiologic Clinics of N. Am. 205, 217 (2011) (based
on clinical, biomechanical, neuropathological, and neuro-
radiological evidence, significant head injury, including
subdural and retinal hemorrhages, may result from low level
falls); Squier, The "Shaken Baby" Syndrome: Pathology and
Mechanisms, 122 Acta Neuropathologica 519 (2011) (same);
Cummings, Trelka, & Springer, Atlas of Forensic Histopathology,
Cambridge Univ. Press (2011) (skull fractures, subdural
hematomas, and retinal hemorrhages have all been found after
short falls); Lantz & Couture, Fatal Acute Intracranial Injury,
Subdural Hematoma, and Retinal Hemorrhages Caused by Stairway
Fall, 56(6) J. Forensic Sciences 1648 (2011) (case study of
infant who fell from short height and had subdural hemorrhage,
midline shift, mild edema, and severe retinal hemorrhages).
     25
       See, e.g., Jones, Martin, Williams, Kemp, & Theobald,
Development of a Computational Biomechanical Infant Model for
the Investigation of Infant Head Injury by Shaking, 55 Med.,
Sci., & Law 291 (2015) (biomechanical study using computational
model suggests shaking cannot generate levels of force necessary
to produce injuries associated with abusive head trauma).
     26
       See Anderst, Carpenter, Abshire, Bleeding Disorders in
Suspected Child Abuse, 131 Pediatrics 1314, 1320-1321 (2013)
(demonstrating that bleeding disorders can cause or aggravate
findings that can be attributed to abuse and recommending more
                                                                  38


    This research appears to have influenced the position of

the AAP regarding the diagnosis of child abuse in head injuries.

In July, 2001, the Committee on Child Abuse and Neglect of the

AAP declared, "Although physical abuse in the past has been a

diagnosis of exclusion, data regarding the nature and frequency

of head trauma consistently support the need for a presumption

of child abuse when a child younger than [one] year has suffered

an intracranial injury."   Shaken Baby Syndrome:   Rotational

Cranial Injuries -- Technical Report, 108 Pediatrics 206, 206

(2001).   In 2009, however, the AAP acknowledged in a policy

statement that "[f]ew pediatric diagnoses engender as much

debate as [abusive head trauma]."   Christian, Block, & Committee

on Child Abuse and Neglect of American Academy of Pediatrics,

Abusive Head Trauma in Infants and Children, 123 Pediatrics

1409, 1410 (2009).   The AAP recognized that the "[c]ontroversy

is fueled because the mechanisms and resultant injuries of

accidental and abusive head injury overlap, the abuse is rarely

witnessed, an accurate history of trauma is rarely offered by

the perpetrator, there is no single or simple test to determine


extensive evaluations to test for presence of these disorders);
Guthkelch, Problems of Infant Retino-Dural Hemorrhage with
Minimal External Injury, 12 Hous. J. Health L. & Pol'y 201
(2012) (due to the complexity of infant brain, "we should not
expect to find an exact or constant relationship between the
existence or extent of retino-dural hemorrhage and the amount of
force involved, let alone the state of mind of the perpetrator.
Nor should we assume that these findings are caused by trauma,
rather than natural causes").
                                                                  39


the accuracy of the diagnosis, and the legal consequences of the

diagnosis can be so significant."   Id.   The 2009 policy

statement no longer spoke of a presumption of child abuse, and

instead declared, "A medical diagnosis of [abusive head trauma]

is made only after consideration of all clinical data," noting

that pediatricians "have a responsibility to consider

alternative hypotheses when presented with a patient with

findings suggestive of [abusive head trauma]."    Id.

    If defense counsel had offered expert testimony at trial

questioning the validity of the scientific foundation of the

diagnosis of shaken baby syndrome, and discussing the

possibility that accidental short falls can cause injuries

generally associated with shaken baby syndrome, the studies

published after July, 2007, and the changes in the AAP policy

statement might have lent more credibility to that expert

testimony, but this generally would not be enough alone to

justify a new trial.   See Commonwealth v. Shuman, 445 Mass. 268,

275-276 (2005) (where defendant offered expert testimony at

trial, proffer of new scientific evidence that constitutes

"mere[] . . . broadening of the research . . . already present

in legal and scientific circles" or "mere addition of further

information to the preexisting debate" would not be "significant

enough to create a substantial risk that the jury would have

reached a different conclusion had the evidence been admitted at
                                                                  40


trial"); Commonwealth v. LeFave, 430 Mass. 169, 181 (1999).

But, here, defense counsel did not present any expert testimony

because he claimed he could not find an expert with "solid

credentials" who could assist the defense.    Consequently, apart

from the brief reference to Dr. Plunkett's research on

accidental falls referenced on cross-examination, the jury heard

nothing that would allow them to have a reasonable doubt whether

Veronica's injuries had been caused by her accidental falls.

Yet, in view of the new research published after trial and the

number of published court cases where such experts have

testified, competent counsel today would, with diligent effort,

have been able to retain such an expert and offer the jury an

alternative interpretation of the evidence.   See, e.g., In re

Fero, 192 Wash. App. 138, 156-157 (2016) ("the medical community

now recognizes that [the constellation of injuries associated

with shaken baby syndrome], which was once believed could only

be inflicted by car accidents, long falls, or child abuse, can

actually be caused by short falls and other low-impact

accidents, in addition to various natural causes"); Ackley, 497

Mich. at 391-392 (noting "prominent controversy within the

medical community regarding the reliability of [shaken baby

syndrome]/[abusive head trauma] diagnoses"); Edmunds, 308 Wis.

2d 385-386 ("a significant and legitimate debate in the medical

community has developed in the past ten years over whether
                                                                  41


infants can be fatally injured through shaking alone, whether an

infant may suffer head trauma and yet experience a significant

lucid interval prior to death, and whether other causes may

mimic the symptoms traditionally viewed as indicating shaken

baby or shaken impact syndrome").

     Therefore, we confront this dilemma:   if the defendant were

deprived of an available defense because counsel was

ineffective, we would determine whether there was a substantial

risk of a miscarriage of justice and, if there was, we would

conclude that the interests of justice require a new trial.     See

Millien, 474 Mass. at 432 ("substantial risk of a miscarriage of

justice" standard is same as prejudice standard under second

prong of ineffective assistance of counsel test).   But what do

we do if we determine that the defendant was deprived of a

substantial defense only because, if the trial were conducted

today, it would be manifestly unreasonable for counsel to fail

to find and retain a credible expert given the evolution of the

scientific and medical research?27


     27
       We emphasize that our focus on the search for a credible
expert is framed by the unusual circumstances of this case.
Where the medical and scientific community is less divided or
where the minority position has less medical or scientific
support, or alternatively, where the defense is weaker relative
to other reasonably available defenses, it is generally not
manifestly unreasonable to consult only with one expert when
that expert offers an opinion that a defense is not viable.
This is especially true where the defense rarely succeeds, such
as a defense of lack of criminal responsibility. See
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    We conclude that our touchstone must be to do justice, and

that requires us to order a new trial where there is a

substantial risk of a miscarriage of justice because a defendant

was deprived of a substantial defense, regardless whether the

source of the deprivation is counsel's performance alone, or the

inability to make use of relevant new research findings alone,

or the confluence of the two.   See Commonwealth v. Brescia, 471

Mass. 381, 388 (2015) ("if it appears that justice may not have

been done, the valuable finality of judicial proceedings must

yield to our system's reluctance to countenance significant

individual injustices").

    Therefore, we need not determine whether it was manifestly

unreasonable in July, 2007, for trial counsel to have failed to



Commonwealth v. Kolenovic, 471 Mass. 664, 675 (2015) (noting
"extreme difficulty in successfully defending a murder case
based on a lack of criminal responsibility defense"). But the
research regarding cases where the prosecutor contends that a
young child was injured by a violent shaking suggests that "the
most important predictor of an acquittal is the defense
presentation of nationally prominent experts who challenge the
science." Tuerkheimer, The Next Innocence Project: Shaken Baby
Syndrome and the Criminal Courts, 87 Wash. U. L. Rev. 1, 37-38
(2009). In cases such as these, where there is strong evidence
that a young child hit his or her head after an accidental fall
shortly before the child's devastating head injuries became
manifest, defense counsel might reasonably choose not to present
an expert at trial to testify to the possibility that a short
fall could have caused the injuries, and might reasonably
decline to pursue a short fall defense at trial, but it is
manifestly unreasonable for counsel to make such a strategic
decision without making a diligent effort to consult with an
expert with "solid credentials" who recognizes the possibility
that short falls can cause severe injuries in young children.
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make the additional effort needed to find an appropriate expert.

It suffices that we conclude that the defendant was deprived of

a defense from the confluence of counsel's failure to find such

an expert and the evolving scientific research that demonstrates

that a credible expert could offer important evidence in support

of this defense.28

     3.    Prejudice.   In evaluating whether there is a

substantial risk of a miscarriage of justice arising from the

deprivation of this defense, we conduct a prejudice analysis

comparable to the analysis we conduct after finding that defense

counsel was ineffective or that newly discovered evidence has

emerged.   See Millien, 474 Mass. at 432 (where it was manifestly

unreasonable for counsel to fail to present defense, we

determine whether "we have a serious doubt whether the jury

verdict would have been the same had the defense been

presented"); Grace, 397 Mass. at 305-306 (newly discovered

evidence warrants new trial where that evidence "would probably

have been a real factor in the jury's deliberations" and its

absence at trial "casts real doubt on the justice of the

conviction").   We have a serious doubt in this case whether the

     28
       Although we conclude that the judge erred in failing to
evaluate under Mass. R. Crim. P. 30 (b), as appearing in 435
Mass. 1501 (2001), whether "justice may not have been done"
because of the confluence of counsel's performance and the
evolving scientific research, we recognize that we can cite no
case presenting the unusual circumstances found here that would
justify such an analysis.
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jury verdict would have been the same had the jury heard expert

testimony regarding the possibility that short falls can cause

severe head injuries in young children.

    Here, the prosecution was able to persuade the jury that it

had eliminated the alternative explanation of accidental short

falls because the only medical expert who testified offered the

opinion that injuries of the type and severity suffered by

Veronica could not have been caused by the short falls described

by the defendant, and the only evidence to the contrary was the

brief reference to Dr. Plunkett's study on short falls, the

findings of which the jury learned from Dr. Wilson were not

widely accepted within the national community of pediatricians

and had not been recognized by the AAP.   If the jury had learned

that injuries of the type and severity suffered by Veronica

could have been caused by short falls of the type described by

the defendant, they might have had reasonable doubt whether the

defendant violently shook Veronica after he left Fletcher to go

upstairs.   A reasonable jury could have found that Veronica fell

down the stairs and later fell off the kitchen stool, and that

one (or the combination) of these falls caused the bump on her

forehead that had grown to the size of a dime when Comeau came

home on her lunch break and grew into a discolored lump by the

time she returned home.   Based on Dr. Wilson's testimony, a

reasonable jury could have found that Veronica could have
                                                                    45


remained conscious after even a severe fall, and lost

consciousness after a lucid interval.   A reasonable jury could

also have inferred that Delilah called the defendant to tell him

that Veronica had fallen, not because of any routine fall, but

because Veronica had fallen after losing consciousness, and that

the defendant found her unconscious when he went upstairs.    The

missing link in the defendant's accident defense was any

credible expert evidence that one or both of these accidental

falls could have caused Veronica's injuries.

    Were an expert such as Dr. Scheller to testify at such a

trial today, the expert could offer the opinion that it is

possible for a child to suffer serious head injuries from an

accidental short fall.   See notes 15 and 24, supra; Millien, 474

Mass. at 435 n.16; In re Fero, 192 Wash. App. at 156-157.     Once

the expert's opinion is challenged on cross-examination, the

expert on redirect examination could cite and explain the

numerous studies published in peer-reviewed journals that

support this proposition.   Such an expert witness on redirect

examination also could cite and explain the numerous studies

challenging the view that shaking alone can produce injuries of

the type and severity suffered by Veronica.    See notes 16 and

25, supra; Millien, 474 Mass. at 433 n.15.     See also Cavazos v.

Smith, 132 S. Ct. 2, 10 (2011) (Ginsburg, J., dissenting),

quoting Edmunds, 308 Wis. 2d at 385 ("[d]oubt has increased in
                                                                  46


the medical community 'over whether infants can be fatally

injured through shaking alone'").   If such an expert were to

cause the jury to doubt whether violent shaking alone could have

caused Veronica's severe injuries, they may ask whether there is

any evidence that Veronica was not only shaken, but perhaps

slammed against the wall or thrown to the floor.   But Fletcher

heard nothing unusual while the defendant was upstairs, and

Veronica did not suffer any skull fracture or neck injuries.

And if such an expert were to cause the jury to question whether

Veronica's injuries were caused by impact trauma rather than

violent shaking, they might more carefully consider whether the

impact trauma described by the defendant -- Veronica's fall down

the stairs and off the kitchen stool -- could have caused her

head injuries.

    Such expert opinion testimony likely would be challenged on

cross-examination or by a prosecution expert called in rebuttal,

where the studies in peer-reviewed journals that support the

prosecution theory of shaken baby syndrome could be cited and

discussed.   We need not determine who would prevail in this

battle of the experts, or whether the defendant would be found

not guilty were it presented.   We need only determine, in the

circumstances of this case, whether there is a substantial risk

of a miscarriage of justice where the jury heard no scientific

or medical expert challenging the majority views on shaken baby
                                                                   47


syndrome and short falls, and where new research has emerged

since the time of trial that would lend credibility to the

opinion of such an expert.   Because we conclude that there is a

substantial risk of a miscarriage of justice here, we cannot

allow this conviction to stand.

    Conclusion.   We conclude that, in the circumstances of this

case, there was a substantial risk of a miscarriage of justice,

and we therefore reverse the denial of the defendant's motion

for a new trial, vacate the conviction, and remand the case to

the Superior Court for a new trial.

                                      So ordered.
