Preliminary Breath Test Laws in New Hampshire

As if being pulled over and given Field Sobriety Tests wasn’t trauma enough, the police officer may ask you to submit to a Preliminary Breath Test.  The Preliminary Breath Tester in New Hampshire is a small hand held machine used to measure your blood alcohol content.  The results of the test help the police officer determine if you are legally driving under the influence and if an arrest is to be made.

The device attempts to measure blood alcohol content by measuring the alcohol contained in your breath as you exhale into the machine.  The machine, which runs on batteries, has a fuel cell that oxidizes the alcohol in your breath as it passes over the fuel cell.  The oxidation process alters the electrical current flowing through the device and it calculated your blood alcohol content based on the change in electrical current.

You are under no obligation to submit to a NH Preliminary Breath Test.  The fact that you refused a Preliminary Breath Test may not be used in court except for determining whether the police officer had probable cause for your arrest.  Thus, you face no penalties for refusing to take the test.  Additionally, the police officer requesting the Pre-Breath Test must advise you that failing to take the test, or taking the test, shall not be construed to prevent or require a subsequent test.

Are Preliminary Breath Tests Accurate?

“They are not accurate” was the sentiment of one local officer when asked his opinion of the reliability of the Preliminary Breath Test.  The primary challenge to the Preliminary Breath Test is its accuracy (or lack thereof).   For example, consider the issue of residual mouth alcohol.  Small amounts of residual alcohol in the mouth can create a falsely high BAC reading.  After you drink alcohol, some alcohol remains behind in the mucosal lining of your mouth.  This is known as “residual mouth alcohol”.  When you exhale into the machine, residual mouth alcohol is picked up by the deep lung air as it passes out of your mouth.  Thus, residual mouth alcohol can impact the results of the Preliminary Breath Test.  Unlike the Breathalyzer breath test at the station, there is no 20 minute waiting period to permit the dissipation of residual mouth alcohol prior to taking the preliminary breath test.

Preliminary Breath Tests Are Unreliable

Numerous courts around the country have found the preliminary breath test results to be unreliable and the results inadmissible at trial.  Remember playing with remote controlled cars as a child?  Remember what happens what happens when the batteries run low?  The Preliminary Breath Test, like a remote control car, runs on “AA” batteries and, as such, is unreliable when the batteries run low.  Other potential avenues of attack include whether the hand held machine was properly calibrated, the officers’ training in the use of the machine and the inherent unfairness of not being able to obtain a second sample of your breath for independent laboratory testing.

If you or a loved one is in need to help with a Driving While Intoxicated case and you are looking to hire a New Hampshire dui attorney for representation, we invite you to contact us at Shepherd & Osborne.  We provide a free consultation and are always happy to discuss your case.

  • Nashua
  • Manchester
  • Concord
  • Bedford
  • Merrimack
  • Salem
  • Derry
  • Londonderry
  • Belknap County
  • Carroll County
  • Cheshire County
  • Coos County
  • Grafton County
  • Hillsborough County
  • Merrimack County
  • Rockingham County
  • Strafford County
  • Sullivan County
603-595-5525