One thing that I have trouble with in the U.S. is how much information the police can compel me to give when stopped on the street. Unless you're operating a motor vehicle (or have some other special circumstance), you don't have to carry ID, but in many States, you do have to show it if you're carrying it, and you usually have to give your name and address regardless. Since this varies from State to State, the national ACLU information is vague, so check with your local branch.