The Constitutional Question of DUI Roadblocks

The US Constitution states clearly that the police are not allowed to simply stop someone and conduct a police investigation unless there are clear facts that indicate that they may be criminal activity present. So, if that is what the US Constitution says, how are DUI roadblocks legal?

This is a good question with no obvious answer. In the case Michigan vs. Sitz, the US Supreme Court reviewed a state supreme court decision in Michigan that struck down DUI roadblocks because they are unconstitutional. The US Supreme Court reverse this decision in a 6-3 ruling.

The chief justice at the time admitted in his majority opinion that DUI roadblocks are a violation of the 4th Amendment. So, he stated that a DUI roadblock really is a violation of the Constitution, but….

He went on to say that it is merely a ‘minor violation,’ and because of all the carnage on the highways, we have to do something about it. According to the majority opinion, there is only a ‘minimal intrusion on individual liberties,’ and this must be weighed against the public need for such roadblocks.

The minority opinion on the case noted that the Constitution does not note exceptions to the rules. The question is whether law enforcement possess probable cause to stop the driver. Their argument was that just because stopping every car at a DUI roadblock might make it easier to stop drunk driving, does not justify pulling over every car without cause.

The majority opinion rested its case on the ‘fact’ that DUI roadblocks are effective, but are they really? According to DUI statistics in the state of Michigan, the lower court had found that ‘the net effect of sobriety checkpoints on traffic safety is infinitesimal and possibly negative.’

Interestingly, the US Supreme Court sent the case back to Michigan, and told the lower court to change its decision. The Michigan Supreme Court stated that DUI checkpoints are not legal under the state constitution in Michigan.

As of today, 12 states do not allow DUI checkpoints or roadblocks. In Florda, DUI checkpoints are legal.