In most states, you are not required to identify yourself or show the police your ID (unless you are in a vehicle). We have been unable to confirm that in Nevada that police try to charge people with obstruction of justice for people who refuse to identify themselves to police. However, if you choose to identify yourself, you are required to tell the truth. It is a crime to lie to federal police agents and it is a crime to give false identification to police in many areas [ed- find a cite for this?]."
Actually the supreme court ruled at least a year ago that you are required to give them your name even if you did nothing wrong and if you don't trust me if they decide to charge you with obstructing or something similar they can make it stick I know they can in NY bc me and my buddies were just hanging out and the cops questioned us and my one friend didn't give his name just to be an ass and they charged him and it did stick it was a nothing charge but he had a much worse night then we did lol