Commonwealth v. Garcia, 123 N.E.3d 766

In July 2010 the defendant (age 19) had a relationship with the fifteen‑year‑old daughter of the eventual homicide victim; earlier he entered the daughter's bedroom with a knife and frightened her.
On July 30 the defendant returned to the house, attacked the stepfather and stabbed the victim (the mother); the daughter witnessed the defendant slice the victim’s throat; defendant later admitted killing the victim.
At trial the defendant conceded he killed the victim but argued the facts supported manslaughter (sudden combat/self‑defense) rather than murder; defense presented an expert on adolescent brain development.
A jury convicted defendant of first‑degree murder (premeditation and extreme atrocity/cruelty) and related offenses; the judge imposed life without parole.
Post‑trial the defendant moved for a new trial alleging partial courtroom closure during closing arguments; the judge held an evidentiary hearing and denied the motion.
Defendant appealed, raising (1) failure to instruct on voluntary manslaughter, (2) as‑applied Eighth/Art. 26 challenge to life without parole based on his age, and (3) partial courtroom closure; the SJC affirmed.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether judge erred by not instructing on voluntary manslaughter	Manslaughter instruction required only if evidence could permit manslaughter verdict	Evidence supported a theory that victim confronted defendant with knife and defendant took it and killed her (sudden combat/provocation)	No error; theory was speculative and not supported by sufficient evidence, so instruction not required
Whether mandatory life without parole is unconstitutional as applied to a 19‑year‑old	State argued Miller/Diatchenko limited to under‑18 and not extendable here	Life without parole for late‑teens/early‑20s offenders is unconstitutional given adolescent brain science	Denied; Miller/Diatchenko apply to under‑18 only; record insufficient to extend protections to 19‑year‑old
Whether partial courtroom closure during closing arguments violated right to public trial	Commonwealth: no official exclusion by court; no affirmative act of closure	Investigator was told to wait outside and told others not to enter, producing partial closure	Denied; no official act of exclusion by court or officer, and judge’s factual findings supported denial
Whether exercise of G. L. c. 278, § 33E to reduce verdict or order new trial appropriate	N/A (court reviews record under §33E)	Defendant sought reduction or new trial under §33E	Denied; after full review court declined to reduce verdict or grant new trial

Commonwealth v. Gulla, 476 Mass. 743 (2017) (manslaughter instruction standard)
Commonwealth v. Pina, 481 Mass. 413 (2019) (jury instruction warranted only when evidence could permit manslaughter verdict)
Miller v. Alabama, 567 U.S. 460 (2012) (mandatory life without parole unconstitutional for offenders under 18)
Diatchenko v. District Attorney for the Suffolk Dist., 466 Mass. 655 (2013) (life without parole violates art. 26 for under‑18 offenders)
Commonwealth v. Vanderpool, 367 Mass. 743 (1975) (courts should not instruct on hypotheses unsupported by evidence)
Commonwealth v. Rakes, 478 Mass. 22 (2017) (deference to trial judge’s factual findings on courtroom closure issues)