empty glass of alcohol

What to Know About Blood Alcohol Concentration (BAC)

The Blood Alcohol Concentration (BAC) is the measure of alcohol content in your blood. However, did you know this plays a crucial part in your driving in Massachusetts? When a police officer suspects you’re operating under the influence (OUI) of alcohol, you will be asked to get a test instantly, and your result will have a serious repercussion on your driving. If you refuse to do so, you’ll immediately get a license suspension for six months.

In this article, we’ll share with you the impact of BAC on your driving in Massachusetts, and how the best lawyers in Boston can help you fight your test result in court.

Blood Alcohol Concentration explained

As mentioned, the BAC is a chemical measure of the ethyl alcohol presence and concentration in your bloodstream. Your results will usually depend on the following factors:

  • Weight
  • Amount of alcohol consumed
  • Duration of drinking
  • Alcohol metabolism speed

However, the alcohol quantity consumed over a given amount of time will determine your intoxication. As you should be aware, driving under the influence of alcohol is against the law. For this reason, your BAC result must not exceed the limit required for driving so that you won’t end up with a hefty fine.

How BAC is measured

If you’re wondering how BAC is measured, it can be performed via the following:

  • Blood test: This involves getting a blood serum sample from you, which will then be sent to the laboratory for testing. From there, the specialist will be able to determine your BAC levels.


  • Breathalyzer test: This involves using a breathalyzer machine that measures the alcohol content in exhaled vapors using infrared spectroscopic analysis. In fact, this is the most commonly administered BAC test.

Other than these two methods, the level can also be measured using your hair, saliva, and urine.

What the law requires for BAC level in driving

To avoid any penalty due to driving under the influence of alcohol, you must take note of the information below. The current BAC limits are as follows:

  • All MA Drivers: A maximum reading of .08 or higher
  • MA Drivers Under 21: A maximum reading of .02 or higher
  • MA Commercial Vehicle Drivers (those with a CDL): A maximum reading of .04 or higher

If you exceed the required limits outlined above, keep in mind that you will be penalized. Here are the penalties that you can face, depending on several factors:

Drivers over 21 years old

  • No prior drunk driving offenses: 180 days license suspension
  • One prior drunk driving offense: Three-year license suspension
  • Two prior drunk driving offenses: Five-year license suspension
  • Three or more prior drunk driving offenses: License suspension

Drivers under 21 years old

  • No prior drunk driving offenses: Three years license suspension

Motorists possessing a Commercial Driver’s License (CDL)

  • 1st refusal: One-year license suspension
  • 2nd refusal: Lifetime license suspension


At this point, you now know what BAC level is and how it must be factored in when driving in Massachusetts. Be sure to consider all the valuable information discussed above to avoid getting a penalty, particularly a license suspension. If you get a BAC test and think the result isn’t accurate or has been tampered with, it’s best to hire a lawyer who can help you bring this to court for reassessment. In the end, remember never to drive when you are under the influence of alcohol!

We’re a criminal law firm in Boston specializing in personal injury, criminal defense, and medical malpractice. If you need the best criminal lawyer to fight for your BAC result in court, get in touch with us today for a free consultation!