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How the police determine blood alcohol concentration

On Behalf of | Jan 6, 2023 | Drunk Driving Charges |

Driving under the influence of drugs or alcohol is illegal in every state. California, like many other states, has specific rules that determine if a driver is drunk. As such, if a driver’s blood alcohol concentration (BAC) climbs above the legal limit then the police will charge the driver with a DUI.

Blood alcohol concentration is the amount of alcohol in someone’s system. If their BAC reaches 0.08% or higher, then they’re driving considered legally “too drunk” to drive, regardless of any other factor (including how well they were actually driving). 

Determining the BAC of a driver requires chemical testing, such as a Breathalyzer test, to be accurate. Here’s what you should know:

Determining reasonable suspicion

Police can’t just ask anyone to take a chemical breath test. Instead, they must have reasonable suspicion. For example, the police may have reasonable suspicion to perform a traffic stop on a driver if they find the driver is swerving, running a red light, visible open bottles of alcohol or the smell of alcohol on the driver’s breath. Any one of these can lead to police requesting a breath test.

Using a breath alcohol content (BAC) test

There are several kinds of sobriety tests. Officers typically have a tool called a breath test, or Breathalyzer, that’s used to measure their blood alcohol concentration. A breath test is a handheld device, about the size and shape of a radio, with a port for people to blow in. 

Other sobriety tests may include a urination test or a blood test – however, these tests often have varying accuracy.

What happens if you refuse a breath test

It’s commonly believed that people can refuse a breath test. While not entirely incorrect, refusal to comply does violate implied consent laws, which can lead to serious complications for your future. Drivers should understand their legal rights during a traffic stop and get immediate assistance if they’re worried about a drunk driving charge.