§ 5.9 ACCIDENT 
The defendant does not have to prove anything in a criminal trial. The Commonwealth must prove beyond a reasonable doubt every element of the crime charged. 
In this case there is evidence that what occurred was an accident. You must therefore determine whether the defendant intentionally committed the act or whether what occurred was an accident.
An accident is defined as an unexpected happening that occurs without intention or design on the defendant’s part. It means a sudden, unexpected event that takes place without the defendant’s intending it.  Stated otherwise, an accident is an unintentional event occurring through inadvertence, mistake, or negligence. 
If an act is accidental, it is not a crime.  When considering the evidence, bear in mind that the defendant does not have to prove anything. The Commonwealth must prove beyond a reasonable doubt that what occurred was not an accident.  If the Commonwealth has failed to prove to you beyond a reasonable doubt that what occurred was not an accident, then you must find the defendant not guilty. 
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 Sandstrom v. Montana, 442 U.S. 510, 524 (1979); Mullaney v. Wilbur, 421 US 684, 701-02 (1975); Commonwealth v. Rodriguez, 370 Mass. 684, 689 (1976).
 Commonwealth v. Ferguson, 30 Mass. App. Ct. 580, 582 n.1 (1991) (quoting civil case Quincy Mutual Fire. Ins. Co. v. Abernathy, 393 Mass. 81, 83-84, (1984), and the Criminal Model Jury Instructions for Use in the District Court, Instruction 9.100 (MCLE, Inc. 3d ed. 2009 & Supp. 2011, 2013)). Accident is also defined as “an unintended happening that results in injury or loss. It is some sudden and unexpected event that takes place.” Commonwealth v. Parker, 25 Mass. App. Ct. 727, 731 n.6 (1989). An accident instruction need not specifically define the term “accident,” as long as it explains the Commonwealth’s burden to prove that the defendant’s intentional conduct caused the crime. See Commonwealth v. McGuane, 77 Mass. App. Ct. 371, 375-76 (2010); see also Commonwealth v. Consoli, 58 Mass. App. Ct. 734, 738 (2003) (where instructions sufficiently covered issues of accidental contact in violation of G.L. c. 209A).
 See Commonwealth v. Figueroa, 56 Mass. App. Ct. 641, 647-51 (2002) (where court distinguishes between two concepts of “accident”).
 Commonwealth v. Repoza, 28 Mass. App. Ct. 321, 328 (1990).
 “Where the evidence fairly raises the possibility of accident, the defendant is entitled upoin request to have the judge instruct the jury that the Commonwealth has the burden of proving beyond a reasonable doubt that the death was not accidental.” Commonwealth v. Jewett, 442 Mass. 356, 370 (2004) (citing Commonwealth v. Zezima, 387 Mass. 748, 756 (1982)); Commonwealth v. Palmariello, 392 Mass. 126, 145 (1984); Commonwealth v. Lowe, 391 Mass. 97, 108-12 (1984); Lannon v. Commonwealth, 379 Mass. 786, 790 (1980); Commonwealth v. Ferguson, 30 Mass. App. Ct. 580, 583 (1991) (When issue is fairly raised, judge is required to instruct jury that the Commonwealth prove beyond a reasonable doubt that killing was not accidental). See Commonwealth v. Chambers, 81 Mass. App. Ct. 624, 630 (2012) (where no instruction required where defense not fairly raised by the evidence).
 Additional References
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Although accident and self-defense are mutually exclusive theories (self-defense being intentional), a charge on each theory might be required by the natue of the evidence. See Commonwealth v. Dyer, 460 Mass. 728, 751 & N. 31 (2011), cert. denied, 132 S. Ct. 2693 (2012); Commonwealth v. Zaccagnini, 383 Mass 615, 616 n.2 (1981); Commonwealth v. Turner, 24 Mass. App. Ct. 902, 903 (1987). An accident instruction is not required sua sponte where the case is defended solely on a self-defense theory. Commonwealth v. Olson, 24 Mass. App. Ct. 539, 544 (1987).
In a nonfelony-murder case, the fact that the shooting was accidental negates the intent element required for murder. However, in a felony-murder case accident does not negate intent. Commonwealth v. Griffith, 404 Mass. 256, 260-61 (1989). In Commonwealth v. Power-Koch, 69 Mass. App. Ct. 735 (2007), the Appeals Court reversed the manslaughter conviction because the trial judge refused to instruct on accident, which was the defendant’s only defense. The trial judge opined that pointing a weapon at someone was reckless as a matter of law, regardless of the reason for doing so. The defense argued that there was evidence that the defendant acted negligently rather than recklessly, and that it was a jury question.