The Supreme Court has ruled that warrantless breath tests are constitutionally proper but warrantless blood tests are not.
In Birchfield v. North Dakota the Supreme Court reviewed cases from North Dakota and Minnesota relating to refusals to take a breathalyzer test (ND) and blood test (MN).
In the opinion, Justice Alito noted, “The impact of breath tests on privacy is slight, and the need for BAC testing is great.” Alito further noted, “We reach a different conclusion with respect to blood tests. Blood tests are significantly more intrusive, and their reasonableness must be judged in light of the availability of the less invasive alternative of a breath tests.”
While a clear victory for roadside breathalyzers for combating DUI, the decision raises law enforcement issues for the increasing challenge of testing for drug impaired drivers. Breathalyzers are of little use for drug detection and blood tests have been the preferred law enforcement option for determining impairment.