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SJC-11659

                COMMONWEALTH   vs.   EMMANUEL OKORO.



       Plymouth.     September 3, 2014. - March 23, 2015.

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


Homicide. Constitutional Law, Sentence, Cruel and unusual
     punishment, Parole, Separation of powers. Due Process of
     Law, Sentence, Parole. Parole. Witness, Expert.
     Evidence, Expert opinion. Defense of Others. Practice,
     Criminal, Sentence, Parole, Instructions to jury.



     Indictment found and returned in the Superior Court
Department on February 29, 2008.

     The case was tried before Paul E. Troy, J.; a motion for a
new trial, filed on January 7, 2011, was considered by him; a
motion for a new trial, a reduction in verdict, and
resentencing, filed on September 13, 2012, was heard by him; and
a motion for reconsideration was considered by him.

     The Supreme Judicial Court granted an application for
direct appellate review.


     Ruth Greenberg for the defendant.
     Matthew Libby, Assistant District Attorney, for the
Commonwealth.
     The following submitted briefs for amici curiae:
     Jeanne M. Kepthorne for Markeese Mitchell.
                                                                      2


     Barbara Kaban, Committee for Public Counsel Services, for
Youth Advocacy Division, Committee for Public Counsel Services,
& others.
     Laura M. Banwarth for Massachusetts Association of Criminal
Defense Lawyers.
     Richard L. Goldman for Terrance Pabon.


    BOTSFORD, J.    The defendant, Emmanuel Okoro, appeals from

his conviction of murder in the second degree.   He was fifteen

years old at the time of the offense, January 1, 2008.     Pursuant

to the sentencing statutes then in effect, the defendant

received a mandatory sentence of life imprisonment with

eligibility for parole after fifteen years.   The defendant

argues that in light of the United States Supreme Court's

decision in Miller v. Alabama, 132 S. Ct. 2455, 2460, 2469

(2012), and this court's decision in Diatchenko v. District

Attorney for the Suffolk Dist., 466 Mass. 655, 658 (2013)

(Diatchenko I), the defendant's mandatory life sentence

constitutes a cruel and unusual punishment in violation of both

the Eighth Amendment to the United States Constitution and art.

26 of the Massachusetts Declaration of Rights, and also violates

constitutional guarantees of due process and separation of

powers.   The defendant further argues that his conviction should

be overturned because (1) the trial judge erroneously prevented

him from introducing expert testimony and arguing that the way

the brain develops in children and adolescents makes the

condition of being a youth itself a mitigating factor to be
                                                                   3


considered in determining whether the defendant was capable of

forming the requisite mental state for murder; and (2) the judge

erred in declining to instruct the jury on defense of another.

For the reasons discussed below, we conclude that the

defendant's sentence does meet the requirements of the Eighth

Amendment and art. 26, as well as other constitutional rights,

and we reject the defendant's challenges to his underlying

conviction.

    Background.   1.   Facts.    Although witnesses' accounts

differed substantially and included contradictory testimony as

to the exact events on the night of the killing, the jury could

have found the following.   On December 31, 2007, the defendant,

aged fifteen, had been drinking and smoking marijuana with

friends and family and was very drunk.    Eventually, the

defendant and his companions, including his sister, Iesha

Strickland, attempted to go to a nearby New Year's Eve party,

but they were turned away at the door by the victim, Markeen

Starks, and another young man.    The victim was known to the

defendant and his sister, and had been involved in a series of

violent incidents that appeared to constitute retaliation

against Strickland after she had spoken to the police regarding

an earlier killing.

    At some point before midnight, the defendant and his

companions left the site of the New Year's Eve party and went
                                                                      4


home.     After the party ended, a crowd gathered outside the party

site and a fight broke out.     The defendant and his companions

saw this crowd and went toward it, and this time, the defendant

was carrying a knife.     The defendant and the victim confronted

one another, and although it is unclear who started the physical

fight between them, the defendant stabbed the victim multiple

times.1    The victim ultimately died from these wounds.

     The defendant presented evidence at trial concerning the

level of his cognitive functioning, as well as concerning his

psychological profile and family background.     In particular, the

defendant was tested shortly after the stabbing incident and

found to have an intelligence quotient (IQ) score of 75 or 76,

which placed him in the fifth percentile for youths his age in

terms of cognitive functioning.     This level of cognitive

functioning has been characterized as "borderline deficient,"

and is associated with difficulties in problem solving, flexible

thinking, and detection of options.     In addition, psychological

testing indicated that although the defendant was not severely

mentally ill and was able to perceive reality accurately, he was

vulnerable to "emotional disregulation," meaning that under

stressful conditions he had a tendency toward simplified

approaches to problem solving and being primarily influenced by

     1
       We discuss these events in further detail infra, as they
relate to the defendant's claim of error regarding the trial
judge's decision not to instruct the jury on defense of another.
                                                                      5


emotions.    The defendant also previously had been diagnosed with

oppositional defiant disorder, which is typically associated

with rule breaking and "profoundly annoying" behaviors, although

not typically with violence.

    A forensic psychologist who examined the defendant opined

that much of the defendant's personality presentation could have

been related to the combination of his cognitive limitations and

his history of "exposure to chronic and severe domestic

violence."   In particular, the defendant suffered abuse at the

hands of his father for approximately two years, including

punishments such as being forced to stand with his hands in the

air for hours at a time or to kneel on hard, uncooked rice and

salt.   At around age ten, the defendant was removed from his

parents' home and placed in foster care, where he remained for

three and one-half years.     During that time, he went through

seven different foster homes due to behavioral problems, and he

eventually went to live at a group residential home for youth.

By the time the defendant was about thirteen years old, his

father had been deported to Nigeria, and the defendant was

allowed to return to live with his mother, but by then he was

struggling with poor anger management, disruptive behavior, and

alcohol abuse problems.     Although he was taking several types of

prescribed medications to help with his behavior when he

returned to his mother, his mother decided to "wean him off"
                                                                     6


these medications, and instead allowed him to drink alcohol and

smoke marijuana, because it kept him "more calm."

     2.   Procedural history.   In February, 2008, the defendant

was indicted on a charge of murder in the first degree, and he

was tried in December, 2010.    The jury found the defendant

guilty of murder in the second degree,2 and he was sentenced to

life imprisonment with parole eligibility after fifteen years.

See G. L. c. 265, § 2, as amended through St. 1982, c. 554, § 3;

G. L. c. 127, § 133A, as amended through St. 2000, c. 159,

§ 230.    See also G. L. c. 119, § 72B, inserted by St. 1996,

c. 200, § 14.   On January 7, 2011, the defendant moved for a new

trial or, alternatively, for a reduction of the verdict to

manslaughter pursuant to Mass. R. Crim. P. 25 (b) (2), as

amended, 420 Mass. 1502 (1995).    He also filed a notice of

appeal from his conviction on January 13, 2011.    The trial judge

denied the defendant's motion without a hearing.    Thereafter,

the defendant's new appellate counsel filed on the defendant's

behalf a renewed motion for a new trial and a request for

resentencing.

     In the renewed motion, the defendant argued that due to his

young age, he should be entitled to individualized resentencing


     2
       The judge had instructed the jury on the crimes of murder
in the first degree on theories of deliberate premeditation and
extreme atrocity or cruelty, murder in the second degree, and
voluntary and involuntary manslaughter.
                                                                       7


at which his age could be taken into account.     The trial judge

denied the motion.      The defendant later requested

reconsideration of the denial in light of this court's recent

decisions in Diatchenko I, 466 Mass. 655, and Commonwealth v.

Brown, 466 Mass. 676 (2013).     In denying the defendant's

request, the trial judge stated that although he was "no[t]

unsympathetic to the defendant's plight," "[a]ge, remorse and

abusive upbringing and rehabilitation" were not grounds to allow

the request under rule 25 (b) (2).

     The defendant filed an appeal in the Appeals Court from the

denials of his motion for a new trial and his request for

reconsideration, which was consolidated with the pending appeal

from his conviction.     This court granted the defendant's

application for direct appellate review.3

     Discussion.   1.     Constitutionality of the defendant's

sentence.   a.   Eighth Amendment and art. 26.    At the time of the

defendant's offense, every conviction of murder in the second

degree, regardless of a defendant's age at the time the offense

was committed, required a mandatory sentence of life


     3
       We acknowledge the amicus briefs submitted in support of
the defendant by the Youth Advocacy Division, Committee for
Public Counsel Services; American Civil Liberties Union of
Massachusetts; Campaign for the Fair Sentencing of Youth;
Citizens for Juvenile Justice; End Mass Incarceration Together;
and Hon. Gail Garinger (ret.); by the Massachusetts Association
of Criminal Defense Lawyers; by Markeese Mitchell; and by
Terrance Pabon.
                                                                  8


imprisonment with eligibility for parole after fifteen years.4

The defendant argues that because he was a juvenile at the time

of the offense, this mandatory life sentence, despite his


     4
       In particular, G. L. c. 265, § 2, as amended through St.
1982, c. 554, § 3, provided in relevant part: "Whoever is
guilty of murder in the second degree shall be punished by
imprisonment in state prison for life. . . ." General Laws
c. 127, § 133A, as amended by St. 2000, c. 159, § 230, provided
in part: "Every prisoner who is serving a sentence for life . .
. shall be eligible for parole . . . [at] the expiration of
fifteen years of such sentence." In addition, G. L. c. 119,
§ 72B, inserted by St. 1996, c. 200, § 14, provided: "If a
person is found guilty of murder in the second degree committed
on or after his fourteenth birthday and before his seventeenth
birthday . . . , the superior court shall commit the person to
such punishment as is provided by law. Said person shall be
eligible for parole under [G. L. c. 127, § 133A,] when such
person has served fifteen years of said confinement."

     The Legislature amended this punishment scheme in 2012,
such that a conviction of murder in the second degree for an
adult offender now carries a mandatory sentence of life
imprisonment with the sentencing judge to set the date of parole
eligibility to begin no earlier than after fifteen years and no
later than after twenty-five years. G. L. c. 127, § 133A, as
amended through St. 2012, c. 192, §§ 37-39 (providing that
minimum parole term is now set according to G. L. c. 279, § 24);
G. L. c. 279, § 24, as amended through St. 2012, c. 192, § 46.
The statutes were amended again in 2014, but the mandatory life
sentence with parole eligibility after fifteen to twenty-five
years for murder in the second degree remains the same. See
G. L. c. 265, § 2, as amended through St. 2014, c. 189, § 5;
G. L. c. 279, § 24, as amended through St. 2014, c. 189, § 6.
Of more direct relevance here, with respect to defendants
between fourteen and eighteen who are convicted of murder in the
second degree and are subject to sentencing under G. L. c. 119,
§ 72B, although § 72B was amended in 2013 and again in 2014, the
Legislature did not change the fifteen-year parole eligibility
date for this cohort. See G. L. c. 119, § 72B, as amended by
St. 2013, c. 84, §§ 24, 24A; G. L. c. 119, § 72B, as amended by
St. 2014, c. 189, § 2. The 2013 amendments expanded the class
of persons covered by § 72B to include seventeen year old
defendants. St. 2013, c. 84, §§ 24, 24A.
                                                                   9


eligibility for future parole, is unconstitutional.   Although

the defendant grounds his claim in both the Eighth Amendment and

art. 26, the thrust of his argument is essentially that the

Eighth Amendment, as explicated in the United States Supreme

Court's decision in Miller, 132 S. Ct. 2455, requires

individualized sentencing by the "sentencer" -- the judge -- in

every case in which a juvenile homicide offender5 receives a life

sentence.6

     We agree with the defendant that certain language in Miller

can be read to suggest that individualized sentencing is

required whenever juvenile homicide offenders are facing a

sentence of life in prison.   See Miller, 132 S. Ct. at 2467

("mandatory penalties [such as life in prison without parole]

preclude a sentencer from taking account of an offender's age

and the wealth of characteristics and circumstances attendant to

     5
       The term "juvenile homicide offender" refers in this
opinion to a person who has been convicted of murder in the
first or second degree and was under the age of eighteen at the
time that he or she committed the murder.
     6
       The defendant does not argue that even if the Eighth
Amendment to the United States Constitution does not demand
individualized sentencing by a judge in his case, art. 26 of the
Massachusetts Declaration of Rights contains an independent
requirement for an individualized, judicially determined
sentence.

     In addition to his argument about the constitutionality of
his punishment, the defendant claims that the sentence violates
his due process rights and also art. 30 of the Massachusetts
Declaration of Rights. We address these claims in part 1.b,
infra.
                                                                   10


it"); id. at 2468 ("in imposing a State's harshest penalties, a

sentencer misses too much if he treats every child as an

adult").   See also id. at 2466 n.6 ("Graham [v. Florida, 560

U.S. 48 (2010),] established one rule . . . for nonhomicide

offenses, while we set out a different one [individualized

sentencing] for homicide offenses").   However, Miller's actual

holding was narrow and specifically tailored to the cases before

the Court:   presented with two juvenile defendants convicted of

murder in the first degree, the Court concluded that a mandatory

sentence of life in prison without parole violated the Eighth

Amendment.   Miller, supra at 2469.7

    This court has construed Miller and its consideration of

individualized sentencing to be limited to the question whether

a juvenile homicide offender can be subjected to a mandatory

sentence of life in prison without parole eligibility.   See

Diatchenko I, 466 Mass. at 668 ("the Supreme Court said in

Miller that on those occasions when a State seeks to impose life

in prison without parole on a juvenile homicide offender, there

    7
       The Court stated: "We therefore hold that the Eighth
Amendment forbids a sentencing scheme that mandates life in
prison without possibility of parole for juvenile offenders.
Cf. Graham [v. Florida, 560 U.S. 48, 75 (2010)] ('A State is not
required to guarantee eventual freedom,' but must provide 'some
meaningful opportunity to obtain release based on demonstrated
maturity and rehabilitation'). By making youth (and all that
accompanies it) irrelevant to imposition of that harshest prison
sentence, such a scheme poses too great a risk of
disproportionate punishment." Miller v. Alabama, 132 S. Ct.
2455, 2469 (2012).
                                                                    11


must be an individualized hearing to evaluate the unique

characteristics of the offender and assess whether this

punishment is appropriate in the circumstances").    See also

Brown, 466 Mass. at 686-688.   Accordingly, Diatchenko I and

Brown, which both involved juvenile homicide offenders convicted

of murder in the first degree, left in place the mandatory life

sentence imposed by the murder sentencing statute, G. L. c. 265,

§ 2, but declared invalid, as applied to the two defendants and

similarly situated juvenile homicide offenders, the portion of

that statute that rendered persons convicted of murder in the

first degree ineligible for parole.    The result for both

defendants was a sentence of life imprisonment with parole

eligibility after fifteen years.   See Diatchenko I, supra at

674; Brown, supra at 688-689 & n.10.

     As this court's decision in Diatchenko I makes clear, we

fully accept the critical tenet of Miller that "children are

constitutionally different from adults for purposes of

sentencing," Miller, 132 S. Ct. at 2464, with "diminished

culpability and greater prospects for reform."    Id.   See

Diatchenko I, 466 Mass. at 669-671.    See also id. at 675 (Lenk,

J., concurring).   But as just stated, to date we have determined

that a mandatory life sentence with the possibility of parole

satisfies the constitutional requirements for juveniles

convicted of murder in the first degree, on the understanding
                                                                   12


that it will be for the parole board (board) to take into

account "the unique characteristics" of such offenders that make

them constitutionally distinct from adults, and to ensure that

such offenders are afforded a "meaningful opportunity to obtain

release based on demonstrated maturity and rehabilitation."

Diatchenko I, supra at 674, quoting Graham, 560 U.S. at 75.

Nevertheless, as we indicated in Brown, we have left open for

future consideration "the broader question whether discretion is

constitutionally required in all instances of juvenile

sentencing."   Brown, 466 Mass. at 688.

     In this case, in contrast to the offenders in Diatchenko I

and Brown, the defendant has been convicted of murder in the

second degree.   Although this offense does not include acts of

deliberate premeditation or extreme atrocity or cruelty, murder

in the second degree is an intentional crime involving the

killing of another person; the severity of the offense, even

when committed by a juvenile offender, goes without saying.    See

Diatchenko I, 466 Mass. at 674.   The Legislature has determined

that every defendant convicted of murder in the second degree

must serve a sentence of life in prison with the possibility of

parole after fifteen years.   See G. L. c. 265, § 2; G. L.

c. 119, § 72B.   While recognizing that "[art.] 26, like the

Eighth Amendment, bars punishments which are unacceptable under

contemporary moral standards" (citation and quotation omitted),
                                                                    13


Libby v. Commissioner of Correction, 385 Mass. 421, 435 (1982),

neither Miller nor Diatchenko I persuades us at the present time

that such a mandatory sentence, imposed on a juvenile offender

who commits murder in the second degree, violates the Eighth

Amendment or art. 26.   For the reasons we next discuss, we

continue to think it sensible to leave for a later day the

question whether juvenile homicide offenders require

individualized sentencing.

     First, the defendant's argument that he is constitutionally

entitled to an individualized, judicially determined, sentence

is premised on Miller,8 but as noted, Miller's requirement of

individualized sentencing was limited to instances where a State

seeks to impose life in prison without parole eligibility on a

juvenile.   See Miller, 132 S. Ct. at 2474-2475.9    It is true that

the defendant here was convicted of a less serious degree of

murder than the juvenile defendants in Miller.      Nevertheless,

even though Miller contains language suggesting that the

requirement of individualized sentences for juveniles may extend

     8
       As previously stated, the defendant does not suggest that
even if Miller does not require individualized sentencing in his
case under the Eighth Amendment, art. 26 does so. See note 6,
supra.
     9
       Our decision in Diatchenko v. District Attorney for the
Suffolk Dist., 466 Mass. 655, 671 (2013) (Diatchenko I), that
art. 26 prohibits not only mandatory but judicially set
discretionary sentences of life without parole for juvenile
homicide offenders provides even broader protection for these
offenders than Miller did.
                                                                    14


beyond sentences of life without parole, we do not read Miller

as a whole to indicate that the proportionality principle at the

core of the Eighth Amendment10 would bar a mandatory sentence of

life with parole eligibility after fifteen years for a juvenile

convicted of murder in the second degree.

     Second, the Supreme Court's determination that youth are

constitutionally different from adults for purposes of

sentencing is of fairly recent origin.     Miller was decided in

2012, and its reasoning principally builds on cases that were

decided in the last ten years -- in particular, Roper v.

Simmons, 543 U.S. 551 (2005), and Graham, 560 U.S. 48 (2010).

See Miller, 132 S. Ct. at 2463-2469.     Although in some areas,

this court has recognized for many years that youth are

constitutionally different from adults,11 until Miller was

decided, we did not embrace the view that a constitutional

distinction exists between juveniles and adults in relation to

sentencing.    See Diatchenko I, 466 Mass. at 659-661, 664, 667.12


     10
          See Miller, 132 S. Ct. at 2463, citing Graham, 560 U.S.
at 59.
     11
       See Commonwealth v. A Juvenile (No. 1), 389 Mass. 128,
134 (1983) (knowing and intelligent waiver of Miranda rights by
juvenile generally requires presence of parent or interested
adult who understands Miranda warnings and can explain them to
juvenile; for juveniles younger than fourteen years of age, no
waiver is effective without this protection).
     12
       Compare this court's decision in Diatchenko's direct
appeal from his conviction, Commonwealth v. Diatchenko, 387
                                                                  15


     It is significant that judicial recognition of this

principle is so recent.   As noted in Diatchenko I, the

determination that youth are constitutionally distinct from

adults for sentencing purposes has strong roots in recent

developments in the fields of science and social science.13

Scientific and social science research on adolescent brain

development and related issues continues.14   At this point, we



Mass. 718 (1982), where we rejected the substance of the
argument that youth are constitutionally different from adults
for sentencing purposes. See id. at 721-722, 725.
     13
       As discussed in Miller and Diatchenko I, research in this
area thus far has been important in confirming what "any parent
knows" about adolescents -- that many who exhibit "transient
rashness, proclivity for risk, and inability to assess
consequences" will grow out of these traits, because the
adolescent brain, particularly in areas related to behavior
control, is still developing. Miller, 132 S. Ct. at 2464-2465 &
n.5. See Diatchenko I, 466 Mass. at 669-670 & n.14. These
observations were particularly important to our conclusion in
Diatchenko I that juvenile homicide offenders can never be
sentenced to life in prison without parole, because such a
sentence requires a determination that the offender is
"irretrievably depraved," a finding that is at odds with the
fact that "the brain of a juvenile is not fully developed,
either structurally or functionally." Id. at 670.
     14
       For example, researchers continue to study the age range
at which most individuals reach adult neurobiological maturity,
with evidence that although some brain systems have fully
matured in most individuals by around age fifteen, other brain
functions are not likely to be fully matured until around age
twenty-two. See Steinberg, Should the Science of Adolescent
Brain Development Inform Public Policy? 50 Ct. Rev. 70, 74
(2014), reprinted from 28[3] Issues in Sci. & Tech. 67 (2012).
Studies are also continuing into the various ways that
environmental factors, such as chronic or extreme stress,
trauma, or neglect can impact brain development and adolescent
behavior. See id. at 76; L. Steinberg, Age of Opportunity:
                                                                 16


cannot predict what the ultimate results of this research will

be, or more importantly, how it will inform our understanding of

constitutional sentencing as applied to youth.    In short, we

appear to deal here with a rapidly changing field of study and

knowledge, and there is value in awaiting further developments.

     Moreover, as is true of the science, the law relating to

juveniles and sentencing continues to change and develop at this

time.     State courts have disagreed as to whether Miller's

holding applies retroactively,15 and the Supreme Court has

indicated that it may again take up the issue of juvenile

sentencing in order to resolve this discrepancy.16    Although



Lessons from the New Science of Adolescence 22-23, 165-167
(2014); Environmental Influence on the Developing Brain: A
Report from the Fifth Annual Aspen Brain Forum, The Dana
Foundation, Nov. 26, 2014, available at http://dana.org/News/
Environmental_Influence_on_the_Developing_Brain
[http://perma.cc/VJ8B-757P]; Inside Neuroscience: Scientists
Examine How Brain Structure and Function Change During
Adolescence, Society For Neuroscience, Sept. 18, 2013, available
at http://www.sfn.org/news-and-calendar/news-and-
calendar/news/middle-spotlight/inside-neuroscience-changes-
during-adolescence [http://perma.cc/Z9P3-5R2U]. New knowledge
in these areas may have important implications for law and
social policy decisions, including decisions that affect
juvenile sentencing.
     15
       Compare, e.g., Diatchenko I, 466 Mass. at 666, and State
v. Mantich, 287 Neb. 320, 342, cert. denied 135 S. Ct. 67
(2014), with State v. Tate, 130 So. 3d 829, 831 (La.), cert.
denied, 134 S. Ct. 2663 (2014), and People v. Carp, 496 Mich.
440, 451 (2014).
     16
       The Supreme Court had recently granted certiorari in a
case that concerned the retroactivity of Miller. See Toca v.
Louisiana, 135 S. Ct. 781 (mem.) (2014). However, prior to oral
                                                                  17


there does not appear to be any case currently before the Court

concerning this issue, the Toca case (see note 16, supra)

indicates a reasonable possibility that the Court may shed

additional light on Miller's full implications and on the

constitutional requirements for juvenile sentencing generally

before too long.   Meanwhile, some States, either judicially or

legislatively, have provided additional sentencing protections

for juveniles beyond the minimum requirements articulated in

Miller.17   Although the rights guaranteed under art. 26 may be

broader than those guaranteed under the Eighth Amendment, art.

26 nevertheless "draw[s] its meaning from the evolving standards

of decency that mark the progress of a maturing society," such

that developments in the area of juvenile justice in judicial



argument in that case, the petitioner's murder conviction was
vacated, resulting in his release, and the Court dismissed the
certiorari petition.
     17
       See State v. Lyle, 854 N.W.2d 378, 400 (Iowa 2014)
(holding unconstitutional under Iowa Constitution all mandatory
minimum prison sentences for youthful offenders). See also Del.
Code Ann. tit. 11, §§ 636, 4204A, 4209, 4209A (permitting
sentences of from twenty-five years to life in prison without
parole for juveniles convicted of murder in first degree in
Delaware, and permitting such offenders to petition for sentence
modification after having served thirty years of their original
sentences and every five years thereafter); W. Va. Code § 61-11-
23 (effective June 6, 2014) (eliminating life sentences without
parole for West Virginia offenders who were under age of
eighteen at time of crime, identifying mitigating circumstances
that must be taken into consideration when sentencing juvenile
offenders, and requiring parole board to take into consideration
diminished culpability of youth during parole hearings for
juvenile offenders).
                                                                   18


opinions and legislative actions at the State, Federal, and

international levels help to inform our understanding of what

art. 26 protects (citation omitted).   See Michaud v. Sheriff of

Essex County, 390 Mass. 523, 533-534 (1983).   Given the

unsettled nature of the law in this area and the indication that

it is still evolving, we think it prudent to allow this process

to continue before we decide whether to revisit our

interpretation of Miller and the scope of its holding.

    Finally, although both juvenile and adult homicide

offenders remain subject to a mandatory life sentence, it is

important to note that there are a number of ways that the

constitutional differences between juvenile and adult homicide

offenders currently are reflected in our sentencing laws. Thus,

while the mandatory punishment for murder in the first degree

for an adult remains life in prison without parole, a juvenile

convicted of this crime is now guaranteed to become eligible for

parole at some point in his or her life.   See Diatchenko I, 466

Mass. at 671.   See also G. L. c. 265, § 2, as amended through

St. 2014, c. 189, § 5; G. L. c. 279, § 24, as amended through

St. 2014, c. 189, § 6.   For murder in the second degree, adult

offenders may be imprisoned for up to twenty-five years before

they become eligible for parole, but juvenile offenders must

become eligible for parole after fifteen years.   See G. L.

c. 279, § 24, as amended through St. 2014, c. 189, § 6; G. L.
                                                                  19


c. 119, § 72B, as amended through St. 2014, c. 189, § 2.     In

addition, the Legislature has ensured that youthful offenders18

who are incarcerated are not restricted in their ability to take

part in educational and treatment programs, or to be placed in a

minimum security facility, solely because of the nature of their

criminal convictions or the length of their sentences; these are

protections not afforded to adult offenders.   G. L. c. 119,

§ 72B, as amended by St. 2014, c. 189, § 2.    And finally, as

discussed infra, juvenile homicide offenders, including those

convicted of murder in the second degree, at their parole

hearings will have access to due process rights.

     In sum, we conclude that at present, a mandatory life

sentence with parole eligibility after fifteen years for a

juvenile homicide offender convicted of murder in the second

degree does not offend the Eighth Amendment or art. 26.

     b.   Due process and art. 30.   The defendant advances two

other constitutional arguments in favor of individualized

sentencing.   First, he asserts that the parole process lacks

significant due process protections such as access to counsel,

and includes no guarantees that the board will take into


     18
       The statute defines this term as including, inter alia,
individuals who have been convicted of crimes committed when
they were between the ages of fourteen and eighteen, if such
crimes are punishable by imprisonment in the State prison and
involve the threat or infliction of serious bodily harm. G. L.
c. 119, § 52.
                                                                   20


consideration any of the attributes of youth identified in

Miller as relevant to the issue of sentencing.   See Miller, 132

S. Ct. at 2468.   Recognizing these issues and how fundamental

they are to ensuring that parole eligibility provides a

"meaningful opportunity to obtain release" for juveniles

sentenced to life in prison, see Diatchenko I, 466 Mass. at 674

(citation omitted), we have today concluded, in Diatchenko v.

District Attorney for the Suffolk Dist., ante      ,      (2015)

(Diatchenko II), that certain due process protections not

available to adult offenders in their parole hearings must be

made available to juvenile offenders convicted of murder in the

first degree.    For the reasons discussed in that case, we

conclude here that the same procedural protections in the parole

process must be provided to juveniles convicted of murder in the

second degree.

    Finally, the defendant argues that a mandatory sentence of

life in prison with eligibility for parole for juvenile homicide

offenders impermissibly vests in the executive branch of

government the power to determine whether juveniles serve their

entire lives in prison, in violation of art. 30's requirement of

separation of powers.    It is true that the grant or denial of

parole is a discretionary act of the board and therefore an

executive -- not judicial -- function.    See Commonwealth v.

Cole, 468 Mass. 294, 302 (2014).   However, as discussed, we have
                                                                  21


thus far concluded that, following Miller, the Eighth Amendment

does not require individualized, discretionary judicial

sentencing of juvenile homicide offenders before these offenders

may be sentenced to life in prison with eligibility for parole.19

Accordingly, the fact that the executive branch, through the

board, is charged with making parole decisions for juvenile

homicide offenders does not violate the principle of separation

of powers, because neither the Eighth Amendment nor art. 26

requires parole decisions to be vested in the judicial branch.20

     It remains for us to address the defendant's claims that

the trial judge erred in two ways:   by prohibiting the


     19
       As stated previously, the defendant appears to restrict
his argument about individualized sentencing to the Eighth
Amendment, and does not involve art. 26. It is clear from the
court's decisions in Diatchenko I, 466 Mass. 655, and
Commonwealth v. Brown, 466 Mass. 676 (2013), however, that we
have not concluded that art. 26 requires this result.
     20
       The defendant raises two additional arguments, one based
on this court's decision in Commonwealth v. Walczak, 463 Mass.
808 (2012), and the other on the court's power under G. L.
c. 278, § 33E, as to why he should have the opportunity to argue
before a court for a sentence to a term of years less than life.
However, Walczak concerned the requirements that apply before a
juvenile may be indicted by a grand jury for the crime of murder
when there is evidence of mitigating circumstances, see Walczak,
supra at 810, and G. L. c. 278, § 33E, applies uniquely to
review of all convictions of murder in the first degree, whether
of adult or juvenile offenders. Thus, neither of these claims
relates to the constitutional requirements for sentencing
juvenile homicide offenders, the fundamental issue here.
Accordingly, we see no reason to exercise this court's power of
superintendence over the courts in order to create an
opportunity for the defendant to argue for a lesser sentence on
either of these bases.
                                                                  22


defendant's expert witness from testifying as to how youth may

limit a defendant's ability to formulate malice, and by refusing

to provide a jury instruction on defense of another.   Neither of

these claims is persuasive.   We address the expert testimony

issue first.

    2.   Expert testimony regarding defendant's age.   Prior to

trial, the defendant notified the court and the Commonwealth

that Dr. Robert Kinscherff, a psychologist who serves as the

director of forensic studies at the Massachusetts School of

Professional Psychology, was expected to testify on the

defendant's behalf regarding the "effect of the defendant's age

and his life experience on his actions in the alleged incident."

The Commonwealth sought to exclude this testimony on the ground

that an expert is not permitted to render an opinion that a

juvenile is unable to form the specific intent required for a

murder conviction.

    The trial judge held a hearing on the issue and concluded

that although an expert witness could not base an opinion on

adolescent brain development generally and conclude from it that

a fifteen year old by definition (i.e., always) is unable to

form the specific intent required for murder, Kinscherff would

be allowed to testify as to this particular defendant's "mental

impairment or condition on the night in question."   The issue

was then revisited at length in a sidebar discussion between
                                                                   23


counsel and the judge during Kinscherff's trial testimony.   The

defendant's trial counsel assured the judge at that time that

any testimony of Kinscherff regarding the neurological

development of a teenager's brain would be tied directly to this

defendant's capacity for impulse control, his response to

threats, and his ability to make decisions, and would relate to

the defendant's intent only in this way.   The judge then

permitted the expert to testify at length regarding the

biological aspects of teenage brain development and how these

aspects may be related to adolescent behavior generally and to

the defendant's behavior specifically.21

     Despite the significant testimony that Kinscherff presented

regarding teenage brain development and the defendant's


     21
       For example, Dr. Robert Kinscherff described some of the
current science regarding child and adolescent brain development
and then connected this information to research findings that
people who may have been more impulsive during their teenage
years "tend over time to become less impulsive, more capable of
making considered judgments, more capable of reflecting on
options that they have and plausible consequences to the
decisions that they make." He also testified that
"[a]dolescents are more stress responsive than most adults."
With regard to the defendant specifically, Kinscherff opined
that even as compared to other adolescents generally, the
defendant appeared to be more vulnerable in areas such as
emotional regulation, impulse control, and balanced decision-
making. He also had more difficulty controlling his temper. His
ability to process threats and control his behavior were likely
further affected by his cognitive disabilities, which may have
caused him to see the world in a "fairly simplistic way"; his
history of exposure to violence and resulting hypervigilance;
his violent social environment; and his intoxication on the
night of the incident.
                                                                   24


individual mental capacity, on appeal the defendant argues that

he was nevertheless denied the right to present a full defense

because Kinscherff was not permitted to testify as to how the

incomplete developmental maturity of the adolescent brain

relates to the ability of a teenager to form the required intent

for malice.   For its part, the Commonwealth asserts that as a

matter of law, youth generally, including those who are fifteen,

have been determined to have the capacity to form the intent

required for murder in the first or second degree, and that

Kinscherff was precluded only from giving expert testimony that

would have touched on this legislatively resolved issue.22    We

conclude there was no error.

     This court previously has acknowledged that, although

children may have not have the maturity fully to appreciate the

consequences of wrongful actions, "that does not mean that a

delinquent child lacks the ability to formulate the specific

intent to commit particular wrongful acts."   Commonwealth v.

Ogden O., 448 Mass. 798, 804 (2007).   Where the Legislature has

determined that a youth is capable of committing certain crimes,

we have noted that "respect for the legislative process means

that it is not the province of the court to sit and weigh

     22
       The Commonwealth also notes that the defendant did not
actually seek to have Kinscherff testify during the trial
regarding the general inability of a teenager to form the intent
for malice. The procedural history on this point is not fully
clear. We choose to address the defendant's claim.
                                                                   25


conflicting evidence supporting or opposing a legislative

enactment."   Id. at 805 n.6, quoting Massachusetts Fed'n of

Teachers, AFT, AFL-CIO v. Board of Educ., 436 Mass. 763, 772

(2002).   Here, the Legislature has enacted G. L. c. 119, § 72B,

which, as it applied to the defendant, directs the Superior

Court to punish individuals who are found to have committed

murder in the first or second degree on or after their

fourteenth birthday and before their eighteenth birthday "as is

provided by law."   Thus, the Legislature has clearly indicated

that youth in the defendant's age group are considered capable

of committing murder, and the trial judge was correct to

preclude the defendant from putting forward evidence that would

have suggested it was impossible for anyone the defendant's age

to formulate the necessary intent to commit this crime.

    However, we also have noted that "[e]xpert testimony 'is

admissible whenever it will aid the jury in reaching a decision,

even if the expert's opinion touches on the ultimate issues that

the jury must decide.'"   Commonwealth v. Federico, 425 Mass.

844, 847 (1997), quoting Commonwealth v. Dockham, 405 Mass. 618,

628 (1989).   Thus, we have long held that expert opinion

evidence pertaining to a defendant's intoxication or mental

impairment is appropriate for a jury to consider when a

defendant is charged with a crime requiring specific intent.

See Commonwealth v. Cruz, 413 Mass. 686, 690-691 (1992)
                                                                  26


(defendant charged with and convicted of murder in first degree;

expert testimony concerning effects of defendant's blood alcohol

level at time of alleged offense should not have been excluded).

Cf. Commonwealth v. Grey, 399 Mass. 469, 469-470, 473-474 (1987)

(defendant charged with murder in first degree and convicted of

murder in second degree; error for judge not to instruct on

manslaughter in light of expert testimony regarding defendant's

cognitive impairment and its effect on his capacity to form

specific intent necessary for malice); Commonwealth v. Gould,

380 Mass. 672, 680-686 (1980) (defendant charged with and

convicted of murder in first degree; error for judge not to

instruct jury that they could consider expert testimony

regarding defendant's psychiatric illness on issue of

defendant's ability to act with deliberate premeditation or

extreme atrocity or cruelty).   This evidence is admissible

because a defendant charged with a specific intent crime may

have been so impaired by intoxication or mental illness that a

jury could find him or her incapable of having had the level of

intent necessary to commit the crime at the time of the

incident.   See, e.g., Cruz, supra at 689-690.

    In light of these principles, the trial judge was correct

in allowing Kinscherff to testify regarding the development of

adolescent brains and how this could inform an understanding of

this particular juvenile's capacity for impulse control and
                                                                  27


reasoned decision-making on the night of the victim's death.

This information was beyond the jury's common knowledge, it

offered assistance to the jury in determining whether the

defendant was able to form the intent required for deliberate

premeditation or malice generally at the time of the incident,

and it did not amount to an opinion that the defendant (or any

other fifteen year old) was incapable of forming the intent

required for murder in the first or second degree simply by

virtue of being fifteen.   In this way, Kinscherff's permitted

testimony aided the jury in reaching a decision by helping them

to understand "both the nature of [the] defendant's mental

condition and its effect on his state of mind at the relevant

time."   Cruz, 413 Mass. at 690-691.23,24


    23
       In drawing the analogy between Kinscherff's opinion
testimony here and cases in which expert evidence is presented
relating to the impact of alcohol consumption or mental illness
on the defendant's ability to form the intent necessary for the
crime, we do not suggest, as the defendant argues, that youth
itself "is a disorder." Rather, a defendant's young age can be
a factor in evaluating the defendant's mental state or in
determining whether the defendant's capacity for self-control
may have been affected at the time of the incident. However,
the mere fact that the defendant was fifteen years old when the
events occurred cannot be the basis in and of itself for a
finding that the defendant lacked the necessary mental state to
commit the crime.
    24
       During oral argument the Commonwealth asserted that
Kinscherff's trial testimony went too far into a discussion of
adolescent brain development research and the scientific bases
for impulsivity and other common traits of teenagers, and that
this testimony impermissibly intruded upon the jurors' ability
to use their common knowledge of teenage behavior in order to
                                                                  28


     3.   Defense of another.    Finally, the defendant argues that

the trial judge committed reversible error in declining to

instruct the jury that the defendant's actions may have been

excused, or that he may have been guilty only of manslaughter,

rather than murder, because he was acting in defense of another

when he stabbed the victim.     The defendant requested such an

instruction, and objected when it was not given.25    The

prejudicial error standard therefore applies on appeal, see

Commonwealth v. Burgos, 462 Mass. 53, 66-67, cert. denied, 133

S. Ct. 796 (2012), but there was no error.

     An actor (defendant) may use force against another in order

to protect a third person when "(a) a reasonable person in the

[defendant's] position would believe his intervention to be

necessary for the protection of the third person, and (b) in the

circumstances as that reasonable person would believe them to


form an opinion about this defendant's mental state at the time
of the incident. However, just as increasingly sophisticated
scientific knowledge of adolescent brain functioning has
assisted in informing our understanding of what punishments may
constitutionally be imposed on juvenile offenders, so, too, do
we believe that this scientific knowledge could assist a jury to
form an opinion as to a defendant's mental state at the time of
his alleged crime. See Diatchenko I, 466 Mass. at 667-668, 669-
670.
     25
       The Commonwealth argues that defense counsel's objection
to the lack of instruction on defense of another was untimely.
However, as the Commonwealth acknowledges, the trial judge
accepted defense counsel's objection, even though it was late.
In addition, the judge noted on the record that defense counsel
had clearly indicated during the charge conference that he was
seeking an instruction on defense of another.
                                                                     29


be, the third person would be justified in using such force to

protect himself."    Commonwealth v. Young, 461 Mass. 198, 208

(2012), quoting Commonwealth v. Martin, 369 Mass. 640, 649

(1976).   It is not necessary for the jury to find that the third

person in fact would have been entitled to use force in self-

defense at the time of the incident in order for the defendant

to invoke this defense; however, the intervening defendant must

have had a reasonable belief that the third person was being

unlawfully attacked.    Young, supra at 209.   "The reasonableness

of the belief may depend in part on the relationships among the

persons involved," but if the defendant uses deadly force in

order to protect another where that amount of force was

unwarranted, the defendant's conduct will not be fully excused

and he or she may still be found guilty of manslaughter.

Martin, supra at 649.    See Commonwealth v. Johnson, 412 Mass.

368, 372 (1992).    A judge must instruct the jury on defense of

another where the evidence when viewed in the light most

favorable to the defendant could support a finding that the use

of force was justified on this basis.    See, e.g., Commonwealth

v. McClendon, 39 Mass. App. Ct. 122, 125 (1995).

    The defendant argues that he was entitled to a jury

instruction on defense of another on the theory that he was

defending his older sister, Strickland, when the offense was

committed.   There was evidence presented at trial that the
                                                                  30


victim and the victim's friend, Elijah Finch, had been involved

in acts of violence directed toward Strickland for some time

before the victim's death.   Specifically, the jury could have

found the following.   Up until the summer of 2007, the defendant

and the victim were friendly with one another, but in July,

2007, Strickland attended a party where she saw Finch waving a

gun in the air, shots were then fired, and a man fell to the

ground.   After Strickland spoke to the police about the

incident, she developed a reputation for having implicated Finch

in the shooting, and she experienced retaliation:   her friends

were physically beaten on two separate occasions, and shots were

fired at the house where the defendant and Strickland both lived

several weeks later.   The victim was present when all three of

these incidents occurred, and he verbally encouraged at least

one of the beatings.   The defendant had been home when the shots

were fired, and he could have been aware of the other incidents

as well due to his relationship with Strickland.    Thus, the jury

could have found that Strickland had a legitimate fear of the

victim and Finch, and that the defendant was aware of this fear.

    Turning to December 31, 2007, the night of the killing, the

jury could have found that Strickland was standing near the

defendant at the moment that the defendant and the victim began

to fight, that the victim was armed with a knife at some point

that night, and that Finch or another friend of the victim's was
                                                                   31


armed with a gun.    Considering this evidence in the light most

favorable to the defendant, the jury could have reasonably

concluded that the defendant was concerned for his sister's

safety that evening, and that there was a general atmosphere of

animosity and fear present.    However, despite this atmosphere of

animosity and the presence of the victim, Finch, and Strickland,

there was no evidence presented that suggested the victim or

Finch directed any immediate, physical threat toward Strickland

that night during or prior to the fight between the defendant

and the victim.    None of the witnesses, including those

favorable to the defendant, testified that the victim or anyone

else appeared to be on the verge of striking or otherwise

harming Strickland at the moment that the defendant and the

victim began fighting.    Strickland herself testified for the

defense that as she and the defendant were walking toward the

location where the defendant and the victim ultimately fought,

Strickland paused to tie her sneaker; while doing so, she heard

someone yell out a warning to the defendant; she then ran

through a crowd of people to where her brother was already

engaged in the fight with the victim; and she stood there

watching the fight.    She also stated that the gun did not appear

at the scene until after the victim and the defendant had begun

to fight,26 and that she herself pushed the defendant out of the

     26
          Although witness accounts differed as to from where Finch
                                                                   32


way of the gun.27   In these circumstances, even when considered

in the light most favorable to the defendant, the evidence does

not support a finding that a reasonable person in the

defendant's position at the time of the fight with the victim

would have felt it necessary to defend his sister against the

victim, much less to do so using violent force.   See Martin, 369

Mass at 649; McClendon, 39 Mass. App. Ct. at 125.

     In sum, we agree with the trial judge that a jury

instruction on defense of another was not warranted on the

evidence presented at trial.

                                    Judgment affirmed.

                                    Orders denying motions for
                                      new trial, for reduction of
                                      verdict, for resentencing,
                                      and for reconsideration
                                      affirmed.




had come -- assuming it was Finch who had the gun, which was
uncertain -- and when Finch had arrived at the scene of the
fight, the testimony of the various witnesses who mentioned the
gun generally accorded with Iesha Strickland's account that the
gun appeared after the victim and the defendant had begun to
fight.
     27
       These aspects of Strickland's testimony did not change
substantially on cross-examination.
    SPINA, J. (concurring in part and dissenting in part, with

whom Cordy, J., joins).   I agree with the opinion of the court

except for part 1.b, "Due process and art. 30," ante at     .     As

to that section, I dissent for the reasons stated in my dissent

in Diatchenko v. District Attorney for the Suffolk Dist., ante

,    (2015).
