A person is guilty of unreasonable belief voluntary manslaughter, more colloquially referred to as "imperfect self-defense," if he knowingly and intentionally kills someone under the unreasonable belief that the killing was justified. See 18 Pa.C.S. § 2503(b). The affirmative defense of self-defense, if accepted, results in an acquittal because it constitutes a justification for the conduct charged. Commonwealth v. Rivera, 603 Pa. 340, 983 A.2d 1211, 1218 n. 6 (Pa. 2009). Commonwealth v. Mouzon, 53 A.3d 738 (Pa. 2012) After drinking all evening the Defendant, after attached by the victim in a bar and being physically beaten, shot the victim once in the head. He was convicted of first degree murder. He claimed self defense, and was precluded from introducing at trial the victim's prior criminal record of aggression. The trial court held that Self Defense was an imperfect affirmative defense for which the defendant bore the burden of establishing as an issue at trial, which the Commonwealth must then disprove. See my article in the Legal Intelligencer, http://www.phila-criminal-lawyer.com/CM/Custom/TOCArticles.asp, about this topic and the new law, http://www.phila-criminal-lawyer.com/CM/Custom/Amendments-to-PA-Self-Defense.pdf. This blog is about the 2012 Supreme Court case of Mouzon discussing this now not-so "Perfect Self Defense". A claim of self-defense (or justification) requires evidence establishing three elements: (a) [that the defendant] reasonably believed that he was in imminent danger of death or serious bodily injury and that it was necessary to use deadly force against the victim to prevent such harm; (b) that the defendant was free from fault in provoking the difficulty which culminated in the slaying; and (c) that the [defendant] did not violate any duty to retreat." A defendant must establish the fact of self-defense by a preponderance of the evidence, before the defense is properly in issue. "There must be some evidence, from whatever source, to justify such a finding." Once the question is properly raised, "the burden is upon the Commonwealth to prove beyond a reasonable doubt that the defendant was not acting in self-defense." Commonwealth v. Black, 474 Pa. 47, 376 A.2d 627, 630 (Pa. 1977). The jury instruction may then be given and the issue becomes one of fact for the fact finder. The Commonwealth sustains that burden of negation "if it proves any of the following: that the slayer was not free from fault in provoking or continuing the difficulty which resulted in the slaying; that the slayer did not reasonably believe that [he] was in imminent danger of death or great bodily harm, and that it was necessary to kill in order to save [him]self therefrom; or that the slayer violated a duty to retreat or avoid the danger." Further, as an evidentiary matter, the PA Supreme Court has held that when self-defense is properly at issue, evidence of the victim's prior convictions involving aggression may be admitted, if probative, either (1) to corroborate the defendant's alleged knowledge of the victim's violent character, to prove that the defendant was in reasonable fear of danger, or (2) as character/ propensity evidence, as indirect evidence that the victim was in fact the aggressor. Only those past crimes of the victim that are similar in nature and not too distant in time will be deemed probative, with the determination as to similar nature and remoteness resting within the sound discretion of the trial judge. Section 505 provides, in relevant part: § 505. Use of force in self-protection(a) Use of force justifiable for protection of the person.-The use of force upon or toward another person is justifiable when the actor believes that such force is immediately necessary for the purpose of protecting himself against the use of unlawful force by such other person on the present occasion. (b) Limitations on justifying necessity for use of force.-* * * * (2) The use of deadly force is not justifiable under this section unless the actor believes that such force is necessary to protect himself against death, serious bodily injury, kidnapping or sexual intercourse compelled by force or threat; nor is it justifiable if: (i) the actor, with the intent of causing death or serious bodily injury, provoked the use of force against himself in the same encounter; or (ii) the actor knows that he can avoid the necessity of using such force with complete safety by retreating or by surrendering possession of a thing to a person asserting a claim of right thereto or by complying with a demand that he abstain from any action which he had no duty to take . . . . Assignment of a burden upon the Commonwealth to disprove self-defense is a relatively recent, and significant, adjustment of law. By its terms, Section 505 does not address the burden of proof or assign the burden to the Commonwealth. Commonwealth v. Mouzon, 53 A.3d 738 (Pa. 2012) In holding that placing the burden on the defendant did not violate due process, decisional law is that federal due process permits States to place a burden on the defendant to prove an affirmative defense by a preponderance of the evidence, so long as the defendant is not thereby required to negate an element of the offense. See also Dixon v. United States, 548 U.S. 1, 126 S. Ct. 2437, 165 L. Ed. 2d 299 (2006) (defense of duress). The affirmative defense of self-defense, if accepted, results in an acquittal because it constitutes a justification for the conduct charged. Commonwealth v. Mouzon, 53 A.3d 738 (Pa. 2012) The Mouzon case went as for to say "Appellee's failure to offer any evidence to support the subjective aspect of his claim of self-defense highlights the difficulties associated with assigning the Commonwealth the burden to disprove a defense where necessary facts are peculiarly within the knowledge and control of the defense. In any event, ...[the evidence in this case] does not remove the necessity that there be some actual evidence to support the elements of the defense when proffered. [T]his case illustrates the wisdom of the common law rule placing the burden upon the defendant to prove self-defense. Although the defense ultimately is subject to objective evaluation, the core is the defendant's "reasonable belief." That is a matter known peculiarly to the defendant, and there is no logical reason such an actor-sensitive defense should be permitted to arise from counsel's speculative inferences from the testimony of others. Commonwealth v. Mouzon, 53 A.3d 738 (Pa. 2012) In other words, a defendant must testify to establish the elements of self-defense. Call to discuss your self-defense case, facts, and the legal burdens.