The United States Supreme Court recently held in three consolidated appeals that the Fourth Amendment permits warrantless breath tests incident to arrest for drunk driving, but not warrantless blood tests.
To combat drunk driving, all states prohibit individuals from driving with a blood alcohol concentration (BAC) over a prescribed level. BAC is generally determined using a blood or breath test. To enforce drivers’ cooperation, states have enacted “implied consent” laws requiring drivers to submit to BAC tests. The initial penalty for refusing these tests was a drivers’ license suspension. Over time, however, states have strengthened their DUI laws and have imposed stricter penalties for defendants with high BAC levels. Therefore, drivers fearing harsher punishments have greater reason to refuse testing. Some states now make it illegal to reject testing.