The law is also going to ask hard questions about "unknowingly". If you're walking around Market St. at 11 PM and some dude stops you and tries to sell you a fancy new bike for $200, complete with a U-lock holder but no U-lock, the law is probably going to say that you should have expected it to be stolen property. If you gave the guy $200 in cash without asking any questions, you probably won't get away saying "I unknowingly purchased stolen goods".