While detention requires only that police have reasonable suspicion that a person is involved in criminal activity, an arrest requires that the officer have probable cause to believe that the person has committed a crime. Although some states require police to inform the person of the intent to make the arrest and the cause for the arrest, it is not always obvious when a detention becomes an arrest. After making an arrest, police may search a person, her belongings, and her immediate surroundings.
Whether an arrested person must identify herself may depend on the jurisdiction in which the arrest occurs. If a person is under arrest and police wish to question her, they are required to inform the person of her Fifth-Amendment right to remain silent by giving a Miranda warning. However, Miranda does not apply to biographical data necessary to complete booking. It is not clear whether a “stop and identify” law could compel giving one’s name after being arrested, although some states have laws that specifically require an arrested person to give her name and other biographical information, and some state courts have held that refusal to give one’s name constitutes obstructing a public officer. As a practical matter, an arrested person who refused to give her name would have little chance of obtaining a prompt release.