Sometimes. The answer depends on whether or not you are in police custody -- that is, whether you are subject to the restraints common to a formal arrest. For example, the U.S. Supreme Court has ruled that the police do not have to provide Miranda warnings during roadside questioning of a motorist detained pursuant to a traffic stop. Thus, roadside questioning about your drinking, drug-taking, or performance on field sobriety tests does not constitute "custodial interrogation." However, once you are arrested -- or restrained by the police in a manner consistent with arrest -- you must be read your Miranda rights.