Coffee Causes Ignition Interlock Violation

This morning I’m at the interlock unit of the Registry of Motor Vehicles in Quincy, attending an Ignition Interlock Violation Hearing for a woman who got two false positive alcohol readings of .180 and .059. The Registry of Motor Vehicles has sent her a violation notice and they have threatened to revoke her license for a period of 10 years for having violated the Mass. Ignition Interlock Law, which prohibits anyone with an interlock restricted license from operating a motor vehicle with a blood alcohol content (BAC) of .02 or above. Here, the woman’s BAC was reported at .180. This is an extremely high reading, as the legal limit in Massachusetts is .08. Her reading was more than double that limit. Based on my extensive experience with the ignition interlock device, this high reading is indicative of contamination, meaning that some contaminant in her mouth was mistaken for blood alcohol. In her case, she was drinking black coffee prior to and while driving. Coffee has been known to produce false positive ignition interlock readings.

Faced with a 10 year loss of license, this client has been extremely distraught, since receiving the ignition interlock violation notice. However, I am confident that the Registry will afford her a full and fair hearing. I will be introducing a 71 page memorandum which explains why the Registry should not revoke her license for this violation, as the readings do not reflect consumed alcohol. The client will testify, under oath, that she consumed absolutely no alcoholic beverages on the date in question or even the day before. 

Anyone who uses an ignition interlock device should be aware that anything consumed immediately prior to or during breath samples can cause interlock device to register an alcohol reading which may result in an ignition interlock violation. Interlock users should only consume water while using the interlock device.