​Implied Consent Laws and How They Got Out of Hand

Posted by Doug Murphy | Feb 28, 2019 | 0 Comments

​The law of driving while intoxicated (DWI) seems like it should be simple and straightforward. It is not. And the U.S. Supreme Court's newfound interest in taking a DWI case shows that the law has been evolving at a rate that requires input from the highest court in the country, once again.

The major developments over the past decade have been the proliferation of implied consent laws that offer law enforcement a way to score a criminal conviction while barely gathering any evidence. These criminalized implied consent laws were actually the reason why the Supreme Court of the United States last dipped its toe into DWI law, in the case of Birchfield v. North Dakota.

Understanding how implied consent laws work, and why it was so controversial when some states criminalized them, is necessary before a discussion of the Birchfield case.

The Role of Implied Consent Laws in the World of DWI

Implied consent laws occupy an important role in the DWI world. When they wrote DWI laws in the 1930s, lawmakers decided that a DWI suspect's blood alcohol content (BAC) would be the Holy Grail of drunk driving evidence – suspects with BAC at or above 0.08% would be deemed “intoxicated” without the need for further evidence.

Of course, this meant that law enforcement had to procure a BAC reading through a breath or blood test. Drivers quickly realized that if they refused the test and waited it out until police obtained a warrant to back up their search for a suspect's BAC, the alcohol would have dissipated from their blood.

So lawmakers added implied consent laws to the books across the U.S. These laws implied that a driver had consented to a chemical BAC test whenever they drove on the road. A driver's refusal was considered a violation of his or her implied consent, which led to administrative sanctions, like an automatic license suspension.

States Add Teeth to Implied Consent Laws

Drunk driving advocacy groups like Mothers Against Drunk Driving (MADD), however, were not satisfied with these implied consent laws. They wanted more, lobbied for it, and lawmakers obliged by adding not just administrative sanctions for implied consent violations, but criminal sanctions for refusing a BAC test in some states.

Suddenly, it was a crime to say “no” to a breathalyzer in the states that passed these laws.

However, because the negative answer is now a crime in these states, the question became a “search” that triggered the driver's Fourth Amendment rights: Police asking a DWI suspect to take a breathalyzer or blood test now either has to have a warrant, which is rare, or their search must fall into one of the few exceptions to the warrant requirement.

DWI Defense Lawyer Doug Murphy Serves Houston Area

These implied consent laws spawned numerous lawsuits that were collected and together brought before the Supreme Court in Birchfield back in 2015. It has barely been four years since Birchfield was decided and already the Court sees the need for re-explaining the intersection of implied consent laws and the Fourth Amendment in the new case State v. Mitchell.

DWI defense lawyer Doug Murphy continues to watch the progress of Mitchell closely. Contact him online or call his Houston law office at (713) 229-8333 if you have been accused of drunk driving.

About the Author

Doug Murphy

Doug Murphy is one of only two Texas lawyers Board Certified in Criminal Law by the Texas Board of Legal Specialization, and also in DWI Defense by the National College for DUI Defense, accredited by the American Bar Association and the Texas Board of Legal Specialization.


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