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 Alaska, following a DUI/DWI arrest, police officers may request the accused to submit to a blood test to determine blood alcohol concentration (BAC). Alaska's per se intoxication level is a BAC of .08 or higher. Under Alaska's implied consent laws, drivers have implicitly agreed to submit to chemical tests (blood, breath, or urine) by accepting a driver's license. Refusal to submit to such tests can lead to consequences including the use of the refusal as evidence at trial, fines, penalties, and an automatic driver's license suspension for at least 90 days. The U.S. Supreme Court has ruled that forced blood draws without a warrant are unconstitutional unless exigent circumstances exist, such as an unconscious suspect where implied consent is presumed. However, if a driver refuses and no warrant is obtained, the refusal itself can still lead to legal penalties independent of the DUI/DWI charge.