§ 5.4.5 Instructions on Specific Topics 
(a) Victim’s Reputation, Past Violence, and Threats Known to Defendant 
In determining whether the defendant was reasonably in fear of death or serious bodily harm, you may consider any or all of the following:
• evidence of the deceased’s reputation as a violent or quarrelsome person, but only if that reputation was known to the defendant; 
• evidence of other instances of the deceased’s violent conduct, but only if the defendant knew of such conduct;  and
• evidence of threats of violence made by the deceased against the defendant, but again, only if the defendant was aware of such threats. 
 . . .
 . . .
 Commonwealth v. Clemente, 452 Mass. 295, 308 (2008) (citing Commonwealth v. Fontes, 396 Mass. 733, 734-35 (1986) (“The judge instructed in regard to the reputation evidence that the jury could consider whether the victim had a reputation as a ‘violent or quarrelsome person that was known to the defendant before the alleged incident.’ That instruction was and is a correct statement of the law”)).
 Commonwealth v. Adjutant, 443 Mass. 649, 654 (2005) (quoting Commonwealth v. Fontes, 396 Mass. 733, 735, 737 (1986) (“Massachusetts has long followed the evidentiary rule that permits the introduction of the victim’s violent character, if known to the defendant, as it bears on the defendant’s state of mind and the reasonableness of his actions in claiming to have acted in self-defense”)); Commonwealth v. Rodriquez, 418 Mass. 1, 5 (1994) (quoting Commonwealth v. Fontes, 396 Mass. 733, 735 (1986); Commonwealth v. Pidge, 400 Mass. 350, 353 (1987) (“It is sell established that a defendant asserting self-defense is allowed to introduce evidence showing ‘that at the time of the killing [she] knew of specific violent acts recently committed by the victim’” because such evidence is relevant in determining “whether the defendant acted justifiably in reasonable apprehension of bodily harm”).
 Commonwealth v. Pidge, 400 Mass. 350, 353 (1987); Commonwealth v. Edmonds, 365 Mass. 496, 502 (1974). Where a defendant has been the victim of abuse, evidence of abuse and expert testimony regarding the consequences of abuse are admissible and may be considered by the jury with respect to the reasonableness of a defendant’s apprehension that death or serious bodily injury was imminent, the reasonableness of a defendant’s belief that he had used all available means to avoid physical combat, and the reasonableness of a defendant’s perception of the amount of force needed to deal with the threat. See G.L. c. 233, § 23F.
(b) Initial Aggressor—Victim’s Past Specific Acts of Violence Not Known to Defendant 
The right of self-defense cannot be claimed by a defendant who was the first to use or threaten deadly force, because a defendant must have used or attempted to use all proper and reasonable means under the circumstances to avoid physical combat before resorting to the use of deadly force. A defendant who provokes or initiates such a confrontation must withdraw in good faith from the conflict and announce to the person (or persons) whom he/she provoked his/her intention to withdraw and end the confrontation without use of force or additional force.  For the purpose of determining who attacked whom first in the altercation, you may consider evidence of the deceased’s [and a third party acting together with the deceased’s] past violent conduct, whether or not the defendant knew of it. 
 . . .
 Commonwealth v. Pring-Wilson, 448 Mass. 718, 733 (2007) (quoting Commonwealth v. Maguire, 375 Mass. 768, 772 (1978) (“right of self-defense ordinarily cannot be claimed by a person who provokes or initiates an assault unless that person withdraws in good faith from the conflict and announces his intention to retire”)).
 Commonwealth v. Pring-Wilson, 448 Mass. 718, 736-38 (2007) (quoting Commonwealth v. Adjutant, 443 Mass. 649, 664 (2005) (evidence of violent conduct, even when defendant did not know of such conduct, admissible to resolve contested identity of likely first attacker; “where the identify of the first aggressors is in dispute and the victim has a history of violence . . . trial judge has the discretion to admit evidence of specific acts of prior violent conduct that the victim is reasonably alleged to have initiated to support the defendant’s claim of self-defense.”)).
(c) Mental Impairment or Voluntary Intoxication as Related to Self-Defense 
[Where there is evidence the defendant at the time of the offense had a mental impairment or was under the influence of alcohol or drugs:]
You may consider the defendant’s mental condition at the time of the killing [crime], including any credible evidence of mental impairment or the effect on the defendant of his/her consumption of alcohol or drugs, in determining whether the defendant actually believed that he/she was in immediate danger of serious bodily harm or death, but not in determining whether a reasonable person in those circumstances would have believed he or she was in immediate danger. 
 . . .
 Cf. Commonwealth v. Barros, 425 Mass. 572, 576 (1997) (“determination as to whether a defendant’s belief concerning his exposure to danger was reasonable may not take into account his intoxication”).
(d) Reasonable But Mistaken Fear of Danger 
[Where thee evidence raises an issue of mistaken belief:]
A person may use deadly force to defend him/herself even if he/she had a mistaken belief that he/she was in immediate danger of serious bodily harm or death, provided that the defendant’s mistaken belief was reasonable based on all of the circumstances presented in the case. 
 . . .
 Commonwealth v. Pike, 428 Mass. 393, 396-97 (1998) (“If the defendant’s apprehension of grievous bodily harm or death, though mistaken, was reasonable, his actions in self-defense may be justifiable”); see also Commonwealth v. Glass, 401 Mass. 799, 808 (1988).
(e) “Castle Law” 
[For self-defense cases not under the “castle law,” G.L. c. 278, § 8A:]
A person must retreat unless he/she cannot do so in safety, or unless retreat would increase the danger to his/her own life. 
[For self-defense cases under the “castle law,” G.L. c. 278, § 8A:]
A person who is lawfully residing in his/her house, apartment or some other dwelling is not required to retreat before using reasonable force against an unlawful intruder, if the resident reasonably believes that the intruder is about to kill or seriously injure him/her or another person lawfully in the dwelling, and also reasonably believes that such force is necessary to protect him/herself or the other person lawfully in the dwelling. 
 These instructions are taken from the “castle” law instructions in the Model Jury Instructions on Homicide 26-27 (2013). For an instruction defining “dwelling” in the context of G.L. c. 278, § 8A, see § 5.4.4(d), above.
 Commonwealth v. Benoit, 452 Mass. 212, 226-27 (2008) (quoting Commonwealth v. Pike, 428 Mass. 393, 398 (1998) (“A self-defense instruction is not required unless there is some evidence that the defendant availed himself of all means, proper and reasonable in the circumstances, of retreating from the conflict before resorting to the use of deadly force. This rule does not impose an absolute duty to retreat regardless of personal safety considerations; an individual need not place himself in danger nor use every means of escape short of death before resorting to self-defense. . . . He must, however, use every reasonable avenue of escape available to him’” [citations omitted])); cf. Commonwealth v. Peloquin, 437 Mass. 204, 212 (2002) (noting in dicta that set of jury “instructions, taken as a whole, explained that a defendant need not retreat unless he can do so in safety, and need not do so when he would increase the danger to his own life.”)
 This instruction is required by G.L. c. 278, § 8A, which provides that, where “an occupant of a dwelling . . . was in his dwelling at the time of the offense and . . . acted in the reasonable belief that the person unlawfully in [the] dwelling was about to inflict great bodily injury or death upon [the] occupant or upon another person lawfully in [the] dwelling, and that [the] occupant used reasonable means to defend himself or such other person lawfully in [the] dwelling[, that] [t]her shall be no duty [the] occupant to retreat from [the] person unlawfully in [the] dwelling.” This instruction is not appropriate where the occupant of a dwelling uses force on another person lawfully in the dwelling. See Commonwealth v. Peloquin, 437 Mass. 204, 208 (2002) (“Nothing in G.L. c. 278, § 8A . . . eliminates the duty on the part of the occupant of the dwelling to retreat from a confrontation with a person who is lawfully on the premises”); see also Commonwealth v. Carlino, 449 Mass. 71, 76 (2007) (instruction not warranted where fatal encounter occurs outside of dwelling, in driveway); Commonwealth v. McKinnon, 446 Mass. 263, 267-68 (2006) (same; outside stairs and porch).
(f) Deadly or Nondeadly Force 
[Where the evidence, viewed in the light most favorable to the defendant, would permit the jury to find that the force used by the defendant in committing the crime was either deadly or nondeadly force, the defendant is entitled to the following instruction on the use of both deadly and nondeadly force in self-defense and the jury shall decide the type of force used.] 
Deadly force is force that is intended to or likely to cause death or serious bodily harm. Nondeadly force, by contrast, is force that is not intended to or likely to cause death or serious bodily harm.  You must determine whether the Commonwealth has proved beyond a reasonable doubt that the defendant used deadly force. If you have a reasonable doubt whether the Commonwealth [sic] used deadly force but are convinced that he/she used some force, then you must consider whether the defendant used nondeadly force in self-defense. if the defendant had reasonable grounds to believe that he/she was in immediate danger of harm form which he/she could save him/herself only by using nondeadly force, and had available him/herself of all reasonable means to avoid physical combat before resorting to nondeadly force, then the defendant had the right to use the nondeadly force reasonably necessary to avert the threatened harm, but he/she could use no more force than was reasonable and proper under the circumstances. You must consider the proportionality of the force used to the threat of immediate harm in assessing the reasonableness of nondeadly force. 
 These instructions are taken from the Model Jury Instructions on Homicide 29-30 (2013). Where the evidence would permit the jury to find that the force used by the defendant was either deadly or nondeadly force, the defendant is entitled to instructions on the use of both deadly and nondeadly force in self-defense and the jury shall decide on the type of force used. See Commonwealth v. Walker, 443 Mass. 213, 217 (2005); Commonwealth v. Baseler, 419 Mass. 500, 503 (1995). But see Commonwealth v. Dyer, 460 Mass. 728, 750 & n. 30 (2011) (defendant not entitled to nondeadly force instruction where he testified that he used only his hands to struggle for gun and it went off accidentally), cert. denied, 132 S. Ct. 2693 (2012).
 Commonwealth v. King, 460 Mass. 80, 83 (2011).
 Commonwealth v. Cataldo, 423 Mass. 318, 325 (1996) (“force neither intended nor likely to cause death or great bodily harm”) see Commonwealth v. Lopes, 440 Mass. 731, 739 (2004) (using one’s fists is nondeadly force).
 Commonwealth v. King, 460 Mass. 80, 83 (2011) (“(1) the defendant had reasonable concern for his personal safety; (2) he used all reasonable means to avoid physical combat; and (3) ‘the degree of force used was reasonable in the circumstances, with proportionality being the touchstone for assessing reasonableness”) (quoting Commonwealth v. Franchino, 61 Mass. App. Ct. 367, 368-69 (2004)): Commonwealth v. Adams, 458 Mass. 766, 774 (2011); Commonwealth v. Lopes, 440 Mass. 731, 739 (2004) (“use of nondeadly force is justified at a lower level of personal safety’”) (quoting Commonwealth v. Baseler, 419 Mass. 500, 502-03 (1995); Commonwealth v. Noble, 429 Mass. 44, 46 (1999).