After stopping a driver for suspected DWI, the driver refuses a breath test. You want to obtain a blood sample. You may do so if:

• A. You have first obtained a search warrant.
• B. The driver consents to a blood draw.
• C. The officer has probable cause to believe intoxication.
• D. The blood draw is automatic after refusal.

Answer: (A)

Blood draws are searches under the Fourth Amendment, so you can’t compel a blood sample after a DWI suspect refuses a breath test unless you have authority to do so. In this situation, the proper authority is a search warrant obtained from a magistrate, based on probable cause that the driver was intoxicated and that the blood will provide evidence of intoxication. Once the warrant is issued, a qualified medical professional can perform the draw.

Consent would allow a blood draw without a warrant, and mere probable cause to believe intoxication isn’t enough by itself to bypass the warrant requirement. There isn’t an automatic blood draw merely because the person refused the breath test.