The Fourth Amendment’s prohibition on unreasonable searches and seizures means law enforcement must obtain a warrant or else rely on a specific exception to the warrant requirement, like the consent of the person being searched, to investigate a crime.

But can Colorado law provide blanket consent for police to draw the blood of alleged drunk drivers, even if the suspect insists he does not give his consent to the “search?”

On Tuesday, members of the state Supreme Court acknowledged two competing views on the ability of motorists to revoke the consent that state law has created for them. On the one hand, the court, in its own 2017 decision of People v. Hyde, stated categorically that “there is no constitutional right to refuse a blood-alcohol test.”

“I don’t know what that Hyde author was thinking, by the way,” quipped Justice William W. Hood III during oral arguments, to laughter. Hood was the author of the Hyde decision.

On the other hand, two years after Hyde, the U.S. Supreme Court weighed in on whether states’ “expressed consent” laws authorizing blood draws of DUI suspects are constitutional. Although a majority was unable to unite around a single rationale, multiple members of the court suggested states could not legislate consent for their citizens.

“I would go further and hold that the state statute, however phrased, cannot itself create the actual and informed consent that the Fourth Amendment requires,” wrote Justice Sonia Sotomayor for herself and two other members.

Given the mixed signals, Christopher Oneil Tarr, who is serving 40 years in prison for running over a man while driving under the influence, has asked Colorado’s highest court to clarify whether the evidence of his blood alcohol content, obtained over his objection, was collected in violation of the Fourth Amendment.

Late one night in August 2016, Tarr was driving drunk in Aurora, well in excess of the speed limit, when he hit and killed Dalton McCreary in a crosswalk. A jury convicted Tarr of vehicular homicide and other offenses.

After the crash, first responders transported Tarr to the hospital. Law enforcement informed him about Colorado’s expressed consent law, in which drivers have automatically agreed to take a blood or breath test for alcohol content when an officer has probable cause to believe they are intoxicated. If a driver refuses, their license may be revoked and the refusal can be evidence at their trial.

At the hospital, Tarr initially refused a blood test. When police learned McCreary had died, they informed Tarr a forcible blood draw was on the table, which is authorized in cases of vehicular homicide. Tarr again declined to provide his consent and the hospital extracted his blood anyway. The results estimated Tarr’s blood alcohol content was four times the legal limit at the time he struck McCreary.

Tarr attempted to block the test results from being used as evidence, but an Arapahoe County judge disagreed, believing the blood draw fit under the consent exception to the Fourth Amendment’s warrant requirement.

A three-judge panel for the Court of Appeals subsequently analyzed whether the expressed consent law authorizing blood draws translates to a suspect’s actual consent to a search, even when he is objecting in real time. Based on the state Supreme Court’s Hyde decision, the panel felt obligated to conclude Tarr had no right to withdraw the consent automatically provided by state law.

On appeal to the Supreme Court, public defender Casey Mark Klekas described the “deal” Colorado’s expressed consent law creates for drivers: They must consent to a blood or breath test when requested in exchange for use of the roads. If they refuse, they will face consequences — the loss of driving privileges and use of their refusal as evidence of guilt.

If part of the “deal” involves circumventing the Fourth Amendment legislatively, he argued to the court, there could be laws automatically authorizing people’s consent to be searched if they walk down Colfax Ave. late at night, for instance.

“The Fourth Amendment is a limit on governmental power. The policy arguments are real, but the Fourth Amendment ultimately controls. Isn’t that the simplest answer here?” asked Justice Richard L. Gabriel.

Senior Assistant Attorney General Brock J. Swanson argued the Supreme Court had options for how to resolve the appeal. It could double down on its previous conclusion that there is no constitutional right to refuse a blood draw or it could deem warrantless blood draws constitutional based on the need to collect evidence before it disappears — known as the “exigent circumstances” exception to the Fourth Amendment.

Hood acknowledged the stakes involved: If evidence of a driver’s intoxication cannot be used at a vehicular homicide trial because the defendant refuses to consent, there is a “much greater chance of acquittal.”

However, some justices suggested that recognizing a suspect’s right to revoke his consent and potentially force police to obtain a search warrant may not be detrimental to every prosecution. Justice Carlos A. Samour Jr. noted that Tarr’s blood alcohol level, even several hours after the accident, was still elevated.

“If we had a different regime,” added Hood, “presumably they would find ways to do it (get a warrant) faster.”

The case is Tarr v. People.