Following a person’s arrest for a DUI/DWI criminal offense, police officers will ask the accused/defendant to submit to a blood test or blood draw in which a qualified person such as a nurse at the police station or hospital will draw the defendant’s blood (usually from the arm) into a vial to be tested for alcohol concentration and ultimately to determine whether the person is per se intoxicated. Per se intoxication is intoxication by definition—as defined in the state’s statutes, which is often a blood alcohol concentration (BAC) of .08 or higher.

All states have implied consent laws that make a driver’s consent or agreement to submit to a blood, breath, or urine test (a chemical test) when requested by a law enforcement officer a condition of the driver’s acceptance of a driver’s license offered by the state. Despite implied consent laws, in 2013 the United States Supreme Court held that if a person refuses to submit to having their blood drawn the police cannot draw the blood by force without a search warrant, as required under the Fourth Amendment to the United States Constitution. But more recently the Supreme Court upheld a nonconsensual blood draw of an unconscious person suspected of driving under the influence—based on the state’s implied consent laws and the exigent circumstances exception to the Fourth Amendment's warrant requirement.

And if a driver refuses to take a blood or breath test there are other consequences even if the police do not secure a search warrant for the blood draw—including admission of the refusal in evidence at trial, fines, penalties, and automatic suspension of the driver’s license for a year or more.

In North Carolina, as in all states, implied consent laws require drivers to submit to chemical tests (blood, breath, or urine) for the purpose of determining blood alcohol concentration (BAC) if they are arrested for a DUI/DWI offense. North Carolina's per se intoxication BAC level is .08 or higher. Refusal to submit to a chemical test following a DUI/DWI arrest can lead to immediate consequences, including the automatic suspension of the driver's license for at least one year, fines, and penalties. Additionally, the refusal can be used as evidence against the defendant in a court of law. Following the 2013 U.S. Supreme Court decision, police officers in North Carolina must obtain a search warrant to conduct a blood draw if a suspect refuses, unless exigent circumstances exist, such as the suspect being unconscious. This is to comply with the Fourth Amendment protections against unreasonable searches and seizures. However, the Supreme Court has also recognized that nonconsensual blood draws from unconscious individuals may be permissible under certain conditions, such as implied consent laws coupled with exigent circumstances.