Commonwealth v. Philbrook, 475 Mass. 20

Defendant shot and killed his former wife in the street in Everett in August 2007; he did not dispute being the shooter. Neighbors witnessed the shooting and police arrested him shortly thereafter.
Defendant claimed lack of criminal responsibility: he argued an organic brain disease (frontal lobe atrophy) plus prescription medications (including ropinirole/Requip) and substance abuse produced compulsive behavior and delusional belief that the victim had stolen his money.
Commonwealth presented evidence of the defendant’s escalating monetary preoccupations and threats in the days before the killing, and evidence that two days earlier he had deliberately assaulted a club patron with a baseball bat over an alleged debt.
Trial judge admitted the prior baseball-bat assault as prior-bad-act evidence to prove motive, state of mind, and to rebut the insanity/lack-of-responsibility defense.
During trial juror misconduct surfaced: three jurors had discussed the case before deliberations and one juror was dismissed; remaining jurors were extensively voir dired and the judge denied a mistrial and a request to designate another juror an alternate.
Jury convicted the defendant of first-degree murder (premeditation) and weapons offenses; defendant appealed challenging (1) admission of prior-bad-act evidence, (2) prosecutor’s use of that evidence in closing, (3) juror misconduct handling, and (4) sought reduction of verdict under G. L. c. 278, § 33E.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Admissibility of prior bad-act (bat attack) evidence	Commonwealth: evidence probative of motive/state of mind and to rebut lack-of-responsibility defense	Philbrook: evidence was impermissible propensity evidence and unduly prejudicial	Admitted — judge did not abuse discretion; probative value outweighed prejudice
Prosecutor’s closing use of prior-act evidence	Commonwealth: tied prior act/anger to conscious, deliberate decisions rebutting delusion/compulsion defense	Philbrook: prosecutor impermissibly argued propensity and improper speculation about other crimes	No reversible error — remarks were proper rebuttal and contextualized, not propensity-only appeals
Juror misconduct and mistrial request	Commonwealth: judge’s voir dire and curative instructions preserved impartial jury	Philbrook: premature juror discussion and comments showed juror(s) biased; requested mistrial/alternate	Denied — judge’s dismissal of one juror, extensive individual voir dire, and curative instructions were adequate; no abuse of discretion
Reduction of verdict under G. L. c. 278, § 33E	Philbrook: weight of evidence supports manslaughter/second-degree murder given compulsive/delusional defense	Commonwealth: evidence supports first-degree deliberate premeditation	Denied — court declines to reduce; affirmed convictions

Commonwealth v. Howard, 469 Mass. 721 (2014) (prior bad acts may be admissible to show intent, motive, or state of mind)
Commonwealth v. Helfant, 398 Mass. 214 (1986) (limits on using prior acts solely to show propensity)
Commonwealth v. Anestal, 463 Mass. 655 (2012) (probative value vs. unfair prejudice balancing standard)
Commonwealth v. Copney, 468 Mass. 405 (2014) (Commonwealth not required to show necessity of prior-act evidence)
Commonwealth v. Mendes, 441 Mass. 459 (2004) (evidence of need/motive admissible to explain context for killing)
Commonwealth v. Guisti, 434 Mass. 245 (2001) (juror remarks bearing on guilt versus extraneous information)
Commonwealth v. Alicea, 464 Mass. 837 (2013) (deference to trial judge on juror impartiality determinations)
Commonwealth v. Carlson, 448 Mass. 501 (2007) (prior hostile acts relevant to state of mind and intent)