Actually this information is not entirely correct. This quote is straight from Erowid guidelines for saying no to police searches.

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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?]."
swanman8907 Reviewed by swanman8907 on . cop question if a cop asks for your name and you did nothing wrong do you have to give it to them? Rating: 5