The United States Supreme Court, in a case known as McNeely v. Missouri, issued an important decision related to Driving Under the Influence, or DUI, and search warrants. The Court decided that in most cases, before the police can force a DUI suspect to give blood, they must obtain a search warrant.
The Fourth Amendment to the United States Constitution prohibits unreasonable searches and seizures. It further states that no search warrant shall issue without probable cause.
In essence, the government cannot search you or your home without a warrant issued by a judge. The judge should not issue the warrant unless the police provide evidence to the judge that there is some good reason to approve the warrant and authorize a search.
There are many exceptions to the warrant requirement. A number of the exceptions apply to motor vehicle stops, including DUI arrests.
Exceptions to the warrant requirement include searches made during an arrest (police can pat you down for weapons in the process of an arrest) and searches in which the police are already in legitimate contact with you and observe something “in plain view” (stopped for a traffic ticket; during the stop, the police see an open container on the floorboard). In addition, searches done with your consent (do you mind if I search your trunk? No go right ahead) and “stop and frisk” searches (officer observes what appears to be a street corner drug transaction and approaches the suspect to question him and then pats him down for weapons) do not require a warrant.
Another exception applies to emergency situations, where the evidence can be easily moved, destroyed or otherwise made to disappear before a warrant can be issued (drugs flushed down the toilet). This exception was pertinent to the McNeely decision.
One of the tools law enforcement has at its disposal is “chemical testing”. This includes breath tests and blood tests.
It is impossible to force someone to blow into a breath machine if he is not so inclined. Blood can be drawn involuntarily; the question before the High Court was whether it could be drawn without a warrant and still comply with the Fourth Amendment? The Court answered in the negative, holding that in most situations, the police were required to first obtain a search warrant.
The state argued that by its nature, the blood alcohol content will decline during the time it takes to obtain a warrant, thus asking the Court to treat this as an emergency exception to the warrant requirement. The Supreme Court allowed that while there may be (as yet undefined) circumstances in which a warrant was not necessary, in most cases, the police are required to seek out a judge and obtain a warrant prior to forcibly drawing blood.
US Supreme Court hears DUI case January 13, 2013, Illinois DUI Lawyer Blawg
Summary of requirements for admission of DUI breath tests in Illinois April 12, 2013, Illinois DUI Lawyer Blawg