Except for the language included in the criteria" "knowledge" (which can be substituted with "callous disregard" or interpreted by a jury as "should have known")..............

For example: a defesne to prosecution is "lack of knowledge" that the firearm was stolen. An innocent claim is the best defense, but even better yet is evidence that the buyer took reasonable steps to ensure the weapon was not stolen or otherwise involved in crime....as stated in previous posts.