In In re Jorge M. (2000) 23 Cal. 4th 866, 872 98 Cal. Rptr. 2d 466, 4 P.3d 297, the high court held that Penal Code section 12280, subdivision (b) required proof of defendant's actual knowledge or negligent failure to know of the weapon's salient characteristics. The statute provides in pertinent part: "Any person who, within this state, possesses any assault weapon, except as provided in this chapter, is guilty of a public offense and upon conviction shall be punished by imprisonment in the state prison, or in a county jail, not exceeding one year." (Pen. Code, 12280, subd. (b).) The court found that whether the statute was a public welfare offense was not obvious. on the one hand, it was aimed at protecting the public by regulating and restricting assault weapons. ( Jorge M., supra, 23 Cal. 4th at p. 872.) On the other hand, it was a wobbler that could be punished as a felony, so the penalty was not light. ( Id. at p. 873.) The high court then analyzed in turn seven factors courts have considered in deciding whether a statute should be construed as a public welfare offense. These factors are: "(1) the legislative history and context; (2) any general provision on mens rea or strict liability crimes; (3) the severity of the punishment provided for the crime ('Other things being equal, the greater the possible punishment, the more likely some fault is required'); (4) the seriousness of harm to the public that may be expected to follow from the forbidden conduct; (5) the defendant's opportunity to ascertain the true facts ('The harder to find out the truth, the more likely the Legislature meant to require fault in not knowing'); (6) the difficulty prosecutors would have in proving a mental state for the crime ('The greater the difficulty, the more likely it is that the Legislature intended to relieve the prosecution of that burden so that the law could be effectively enforced'); (7) the number of prosecutions to be expected under the statute ('The fewer the expected prosecutions, the more likely the Legislature meant to require the prosecuting officials to go into the issue of fault')." ( Jorge M., supra, 23 Cal. 4th at p. 873.) In Jorge M., the court concluded that the Court of Appeal decisions that predated the adoption of Penal Code section 12280, subdivision (b) were not compelling evidence that the Legislature intended section 12280, subdivision (b) to lack a scienter requirement. ( Jorge M., supra, 23 Cal. 4th at p. 877.) This was so for two reasons. First, the precedential history was not clear and definitive; the Supreme Court had not spoken on the issue, but had suggested there was a knowledge requirement in other similar contexts. (Ibid.) Second, the Legislature may have believed there was a significant difference between deadly weapons such as machine guns and sawed-off shotguns, which are easily identifiable, and prohibited assault weapons, which may not be. ( Id. at p. 878.) In Jorge M., the court noted that the serious public threat the assault weapon ban was designed to alleviate required a statutory construction that would not impair effective enforcement and that requiring actual knowledge could impair effective enforcement. ( Jorge M., supra, 23 Cal. 4th at p. 884.) The Jorge M. court resolved the problem with a scienter requirement that was satisfied by proof defendant should have known the salient characteristics of the weapon. ( Id. at p. 885.) In Jorge M., the Supreme Court found no compelling evidence the Legislature intended to dispense with a mens rea requirement in Penal Code section 12280, subdivision (b), but the gravity of the public safety threat, together with the substantial number of prosecutions expected and the potential difficulty of proving actual knowledge, convinced the court to construe the statute to require actual knowledge or negligence in regard to the facts making possession of an assault weapon illegal. ( Jorge M., supra, 23 Cal. 4th at p. 887.)