Q: I was one of two passengers. My friend got pulled over. The officer asked him about drinking, because, he said, “You were weaving.” My friend agreed to a breathalyzer. He wound up getting arrested. What exactly is a breathalyzer and could he have refused?

S.B., Reseda

A: The breathalyzer is a device that law enforcement utilizes, typically during a DUI stop, to obtain an estimate on a person’s blood alcohol concentration. There are two types.

A handheld device (about the size of a walkie-talkie), which is for a preliminary alcohol screening, done before an arrest.

The other is an evidential breath test, larger and said to be more accurate, used after an arrest, commonly at the police station or at the DUI checkpoint. It resembles a small fax machine or small printer, with a screen display and hoses or tubes to blow into.

Your friend could have refused the breathalyzer, if he is at least 21 years of age and not on DUI probation, but may ultimately have been placed under arrest and then subject to testing.

Q: What is the legal blood limit to be deemed driving while impaired in California?

T.B. Westminster

A: For adult drivers (21 and over), a blood alcohol concentration of 0.08 is deemed a DUI offense under California Vehicle Code Section 23152(b).

For drivers under 21 years of age, there is a zero-tolerance rule, so 0.01 blood alcohol concentration is considered a DUI per Vehicle Code Section 23136.

With regard to commercial drivers, holding a commercial drivers license, or someone driving passengers for hire, an alcohol blood concentration of 0.04 or higher is a DUI under Vehicle Code Section 23152(d)/(3).

For drivers on DUI probation, whatever age, 0.01% or higher is a DUI violation pursuant to Vehicle Code Section 23154.

It is important to remember that a DUI charge can still be brought even if your blood alcohol concentration is below the legal limit. The officer may conclude you are impaired based upon a number of factors and observations. This can include your drifting between lanes, driving too slowly or too fast, a sudden turn, erratic breaking and/or slurred speech, difficulty standing, or watery or glassy eyes.

Bottom line, do not drive if you are impaired. It is not worth it!

Ron Sokol has been a practicing attorney for more than 40 years, and has also served many times as a judge pro tem, mediator and arbitrator. It is important to keep in mind that this column presents a summary of the law, and is not to be treated or considered legal advice, let alone a substitute for actual consultation with a qualified professional.