Like many other states, California has an implied consent law which provides that drivers have consented in advance to submitting to a BAC test should they be pulled over on suspicion of drunk driving. Police can give a driver a chemical breath test at the scene and the results can be used as evidence against the driver.
However, in some cases police may need a more sophisticated breath test or may want a blood-based test. For these BAC tests, police generally have to take the driver to a police station or medical facility. This raises issues under the Fourth Amendment to the U.S. Constitution, which prohibits unreasonable search and seizure.
A recent case before the U.S. Supreme Court involved a Wisconsin man who was pulled over on suspicion of drunk driving. Relying on his state's implied consent law, a police officer administered a breath test at the scene that showed the driver's BAC was more than three times the legal limit. Officers drove the man to a police station and then a hospital, where they tried to give him more accurate tests. However, by that time the man was slipping into unconsciousness. Ultimately, they drew his blood for a BAC test while he was unconscious. The test showed his BAC was above the legal limit and prosecutors used this evidence against him when charging him with DUI violations.
The man later argued that the police should have had a warrant before they drew his blood while he was unconscious, and that therefore the evidence should be suppressed as an unreasonable search. Eventually, the Wisconsin Supreme Court ruled that the search was lawful under the implied consent law. The U.S. Supreme Court essentially rejected the state's reasoning, but said the search could fall under the "exigent circumstances" exception to the warrant requirement.
In the recent case, the high court said the evidence was in danger of being destroyed, as the driver's BAC would fall as the alcohol worked through his system, and that this danger presented exigent circumstances.
The decision is not good news for people trying to defend against DUI charges. A good DUI defense lawyer can help defendants understand how the law may apply to the unique circumstances of their case.