Implied consent

Implied consent is consent which is not expressly granted by a person, but rather implicitly granted by a person's actions and the facts and circumstances of a particular situation (or in some cases, by a person's silence or inaction). The term is most commonly encountered in the context of United States drunk driving laws.

Driving while intoxicated

All U.S. states have driver licensing laws which state that a licensed driver has given their implied consent to a field sobriety test and/or a Breathalyzer or similar manner of determining blood alcohol concentration. These laws have generally been upheld by courts as a valid exercise of the states' police power, against challenges under the Fourth Amendment (as a reasonable search and seizure) and Fifth Amendment (as not violative of the right against self-incrimination). This is largely because in the United States, driving is considered a privilege rather than a right, and the state has a legitimate interest in keeping dangerously intoxicated drivers off the road, to prevent injury, property damage, and loss of life. In most states, however, the police must have reasonable grounds for administering a sobriety test.