When police detain and question a person on suspicion of driving while intoxicated (DWI), the Fourth, Fifth, and Fourteenth Amendments to the U.S. Constitution protect that person’s rights. The Fourteenth Amendment officially extended most of the Bill of Rights to state-level law enforcement, meaning that local police are subject to the same constraints as the federal government. In the context of New Jersey DWI cases, the Fourth Amendment states that police cannot detain someone, such as by pulling over their vehicle, without reasonable suspicion of wrongdoing. The Fifth Amendment states that a defendant cannot be forced to testify against themselves, and limits the state’s ability to use certain statements made by defendants against them in court. Exactly when this right against self-incrimination applies has been a matter of ongoing dispute in the courts. The U.S. Supreme Court has made several rulings specifically addressing incriminating statements in DWI cases.
The landmark U.S. Supreme Court case addressing the right against self-incrimination during police interrogation is Miranda v. Arizona, decided in 1966. Information obtained by police from a person, after they have invoked their “right to remain silent” during “custodial interrogation,” is inadmissible in court. While people can refuse to answer police questions at almost any time, Miranda obligates police to advise people of their rights in specific scenarios. Many subsequent court decisions have found that Miranda only applies once a person has been formally placed under arrest and read this list of rights. Whether a person is “under arrest” during a traffic stop is a complicated question.
Police do not typically give Miranda warnings to DWI suspects at the beginning of a traffic stop. Still, officers may ask questions of a driver, and ask the driver to perform field sobriety tests. With some exceptions, courts do not consider this to be a “custodial interrogation” within the meaning of Miranda. Police are therefore not obligated to advise people of their Miranda rights at this point, placing the burden of invoking the right against self-incrimination on the driver.