The Supreme Court has ruled that police may, without a warrant, order blood drawn from an unconscious person suspected of driving under the influence of alcohol, reports NPR .

The Fourth Amendment generally requires police to obtain a warrant for a blood draw. But in a 5-4 vote on Thursday, the court upheld a Wisconsin law that says people driving on a public road have impliedly consented to having their blood drawn if police suspect them of driving under the influence. It also said that "exigent circumstances" permit police to obtain a blood sample without a warrant.

Justices Samuel Alito, Clarence Thomas, Stephen Breyer and Brett Kavanaugh joined Chief Justice John Roberts in the majority vote.

The decision conflicts with previous court rulings in which the justices ruled that a blood draw is a significant bodily intrusion into a person's privacy and that there are less intrusive ways of enforcing drunken driving laws against unconscious motorists — getting a warrant, for instance, which in these tech-savvy days can be done relatively easily and quickly.

Discussing the emergency conditions created by unconscious drivers, Alito said that "forcing police to put off other tasks for even a relatively short period of time may have terrible collateral costs. That is just what it means for these situations to be emergencies," he wrote, in an opinion that was joined by Breyer, Kavanaugh and Roberts.