In the United-States you are not obligated to carry identification papers with you at all times. The only times you have to carry your ID is when you are driving a vehicle or when you are a passenger on a commercial airline.
The Fourth amendment to the United-States Constitution prohibits unreasonable searches and seizures and requires a warrant to be judicially sanctioned. Nevertheless Terry v. Ohio (1968) established that it is constitutionally permissible for the Police to temporarily detain a person based on “reasonable suspicion” that a crime has been committed and to conduct a search for weapons based on a reasonable belief that the person is armed. Following that, Hiibel v. Sixth Judicial District Court of Nevada (2004) confirmed that the name disclosure did not violate the Fourth Amendment. The Court did not rule on whether particular identification card could be required.
Stop and identify statutes are laws that authorize the police to request people to identify themselves and arrest them if they refuse.
The Police prerogatives vary from state to state: they can ask name and address in some states, sometimes the intended destination, the date of birth or even a written identification. In order to stop you the officer must have a reasonable suspicion that a crime had been committed or is about to be committed. Keep in my mind that failure to respond is a violation in many states with stop-and-identify-statutes and may result in an arrest.
Nevertheless, you can always use you right to remain silent or try to determine if the officer had a valid reason to stop you at all. If you are willing to use your right to remain silent you should say so to the officer. If the officer didn’t have a valid suspicious reason to stop you are not legally forced to show him any identification. The best way to verify if the officer had a valid reason to stop you is to calmly ask: “Am I Free to go?” If the answer is yes, just slowly walk away without having to answer any question.
If the officer did apparently have a reasonable reason to stop you and you failed to identify yourself you should consider consulting with an experienced criminal attorney. That would be if you truly believe that the officer improperly stopped you. Moreover if the information you ended up disclosing to the officer lead to your arrest for a different matter, a lawyer will help you make sure that this information won’t be able to be used against you.
Sometimes the vagueness of the law might play in your favour. Indeed being arrested for loitering for example might be considered unconstitutional because the definition of “loitering” is too vague. The definition of loitering is “wandering about from place to place without apparent business, such that the person poses a threat to public safety”. The definition makes it hard to prove and often easy to contest.