Ingersoll v. Palmer

Ingersoll v. Palmer found that DUI checkpoints are “administrative” procedures and police do not need probable cause to stop individual motorists. The court ruling created a set of guidelines that are still used in DUI checkpoints today.

During the 1980s, DUI checkpoints were still a new idea and there was intense controversy over whether they violated people’s constitutional rights. In 1987, the California Supreme Court weighed in on the issue with its landmark ruling in Ingersoll v. Palmer. This case set the rules that checkpoints must use in California to be considered legal.

Ingersoll v. Palmer is an unusual case because it does not involve a specific DUI case. Rather, the case was filed by taxpayers from around California, against a variety of local police chiefs and Highway Patrol commissioners. The taxpayers believed that the new DUI roadblocks being used were unconstitutional. These roadblocks had started after the California Attorney General issued an official opinion that roadblocks could be used if they were set up to “minimize the intrusion on motorists.”

The main complaint in the case was that DUI roadblocks gave police the power to pull over drivers even when there was absolutely no evidence or suspicion of any crime. This runs contrary to the rule that officers must have probable cause for a traffic stop—such as a clear traffic violation, or signs of impaired driving.

The Ingersoll Decision

Unfortunately, the state Supreme Court upheld the legality of roadblocks. They ruled that:

“[T]he primary purpose of the stop here was not to discover evidence of crime or to make arrests of drunk drivers but to promote public safety by deterring intoxicated persons from driving on the public streets and highways.”

In other words, the checkpoint is not considered a chance to investigate crimes, but a way to deter people from driving under the influence at all.

This interpretation makes DUI checkpoints administrative procedures, like airport security checks. At an airport, staff do not suspect each person individually of carrying a weapon, but they check all bags impartially to deter people from bringing weapons at all. Similarly, as long as the DUI checkpoints are fair and impartial, they are legal.

The 8 Rules of Ingersoll

The Ingersoll decision also established eight guidelines that checkpoints must follow. These are:

  • A supervising officer must make all constitutional decisions
  • Motorists must be stopped on a neutral, impartial basis
  • The location must be reasonable
  • There must be safety precautions
  • The time and duration must be reasonable
  • There must be signage for the checkpoint
  • Drivers should be detained for the shortest time possible
  • The checkpoint must be advertised in advance

These rules continue to inform the way DUI checkpoints are set up today. But even now, more than 30 years since the Ingersoll ruling, the rules are often broken—which allows you to defend against your DUI checkpoint arrest.

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