An "Ignition interlock system" is a device that “connects a motor vehicle ignition system to a breath analyzer that measures a driver's blood alcohol level and “prevents a motor vehicle ignition from starting if a driver's blood alcohol level exceeds the calibrated setting on the device.” Md. Transportation Code Ann. § 27-107.
There are three mechanisms that can get an individual accused of DUI into the program. An individual may opt to participate in the ignition interlock program in lieu of contesting the administrative suspension of the driver’s license after a DUI arrest, if their license is valid and they file an election within 30 days of their arrest. In these circumstances, if the individual’s B.A.C is .15 or more, participation is required for 1 year and for 6 months if the B.A.C is between .08 and .15.
Separately, a court has the authority as part of a DUI sentence, or as a term of probation, to require a person to participate in the ignition interlock program for up to three years.
Finally, Maryland law mandates that certain individual participate in the program. If the individual is convicted of a violation of 21-902(a) [driving under the influence of alcohol per se] or 21-902(b)(2) where "the minor who was transported was under the age of 16 years”, participation is required. If the individual's license is suspended or revoked for a violation of 21-902(a) or if the individual's license is revoked for homicide by motor vehicle or life-threatening injury where drugs or alcohol were involved, they likewise must participate in the program. Md. Transportation Code Ann. 16-404.1.
The participant is responsible for the costs of the unit. It is illegal to tamper with the unit, to start a vehicle for someone subject to ignition interlock, or, to ask another to circumvent the interlock device with their breath. Under certain circumstances, the MVA may allow a participant in the ignition interlock program to drive a work vehicle that is not equipped with a device. Md. Transportation Code 27-107.