Typically, when a motorist is pulled over on suspicion of Operating Under the Influence (OUI), a law enforcement officer will ask the driver to exit the vehicle and perform standardized field sobriety tests. Based on observations by the officer, he or she may ask the driver to submit to a breath test (known as a Breathalyzer or Intoxilyzer).
Under Maine law, if there is probable cause to believe a person has operated a motor vehicle while under the influence of intoxicants, that person shall submit to and complete a test. See 29-A §2521. This reading of the statute may leave some feeling as though the breath test is mandatory at the request of a law enforcement officer.
However, under Maine law there are provisions which increase the punishment for people who refuse to submit to an alcohol test. Therefore, it can be inferred that the tests are not absolutely mandatory if the driver is willing to incur increased penalties.