In 2016, the Supreme Court of the United States, in Birchfield v. North Dakota, held that both breath tests and blood tests constitute a search under the Fourth Amendment, concluding that requiring breath tests is constitutional without a search warrant; however, requiring more intrusive blood tests involving piercing the skin is not, as the goal of traffic safety can be obtained by less invasive means.
In 2016, the Supreme Court of the United States, in Birchfield v. North Dakota, held that both breath tests and blood tests constitute a search under the Fourth Amendment concluding that requiring breath tests is constitutional without a search warrant; however, requiring more intrusive blood tests involving piercing the skin is not as the goal of traffic safety can be obtained by less invasive means.