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What is reasonable suspicion and probable cause in a DUI case?

On Behalf of | Apr 12, 2023 | DUI Defense |

Driving under the influence (DUI) of alcohol or other drugs is unlawful and dangerous. In California, you are legally drunk when your blood alcohol concentration (BAC) is 0.08% or more, 0.01% or higher for drivers under 21 years and 0.04 or more for commercial drivers. 

You can be arrested if you are caught driving with these levels. But the police will need reasonable suspicion to stop you and probable cause to arrest you.

Here is the difference between these terms:

Reasonable suspicion 

If the police, based on their training and experience, conclude that you are drunk, they may have reasonable suspicion to stop you. This does not mean having a hunch but identifying questionable behaviors, such as: 

  • Swerving /weaving 
  • Driving extremely below the speed limit 
  • Tailgating 
  • Running a red light/stop sign 
  • Not yielding 
  • Braking excessively/rapid acceleration, and so on.

The police can’t stop you because you are coming from the side of a bar or had parked outside one. They should assess you for some time to determine if your behavior is suspicious. 

Probable cause

Reasonable suspicion may lead to probable cause and then to arrest. When the police stop you with reasonable suspicion of drunk driving, they may administer a breathalyzer and field sobriety tests (FSTs). If your BAC results are above the legal limits or your FSTs show symptoms of intoxication, such as poor balance, slurred speech, feelings of confusion and involuntary vibrating of the eyeball, they may have probable cause to arrest you.

Thus, with reasonable suspicion and probable cause, the police may charge you with a DUI, and accordingly, you may face its consequences.

If you are charged with a DUI, you should determine the best defenses to use to protect your record.