In People v. Westlund (2001) 87 Cal.App.4th 652, the Court announced that section 12520, banning possession of a silencer, includes a scienter requirement. The Court also held that the trial court committed error in failing to instruct on that requirement. Despite the error, the Court concluded that "if instructed properly, a reasonable jury would have concluded appellant knew or should have known of the nature of the silencer." ( Id. at pp. 657-659.) The conclusion was based on the fact that "a person who has substantial and unhindered possession of firearms would be expected to know that the item in question here was a silencer." ( Id. at p. 659.)