A DUI breathalyzer or chemical test is considered a protected search under the 4thAmendment of the U.S. Constitution. This means that police need a warrant with probable cause to conduct a DUI breath, blood or urine test, even under Arizona’s Implied Consent law.
There are a few exceptions to the warrant rule, one of which is voluntarily consent. If the driver expressly consents to a breath or chemical test, the officer is not required to have a warrant.
Arizona courts have held that if a person was coerced by the officer to take the DUI test then their consent is not voluntary (State of Arizona v. Valenzuela, 2016). An involuntary consent does not relieve police of the requirement of obtaining a warrant.