SKOWHEGAN, Maine — A Pittsfield mother allegedly fired for using medical marijuana has sued her former employer in Somerset County Superior Court, according to the Maine chapter of the American Civil Liberties Union.

The ACLU of Maine and Augusta attorney Walt McKee filed the lawsuit Tuesday on behalf of Brittany Thomas of Pittsfield against Adecco Group North America, which hires people for temporary employment.

It is the first employment discrimination case filed in Maine over the use of medical marijuana, McKee said in a telephone interview.

Vannessa Almeida, senior manager for public relations with Adecco, said Tuesday evening in an email that the firm had not received a copy of the lawsuit, so it would be premature to comment on the allegations.

“No patient should be forced to choose between the pain relief she needs to live a normal life, and the employment she needs to support her family,” Zachary Heiden, legal director of the ACLU of Maine, said in the release. “And no employer should be forcing itself into the middle of a decision best made by a patient and her doctor.”

Thomas, who suffers from severe back pain, switched from prescribed narcotic pain medication to medical marijuana in consultation with her doctor, the release said. She felt it controlled her pain without the side effects of traditional prescription painkillers.

She had previously been hired through Adecco, which has an office in Lewiston, to work for United Technology Corp. in Pittsfield assembling smoke detectors, the release said. She was let go when they did not have enough work for her.

Thomas was called by Adecco to return to UTC when additional work was available, the release said. Adecco required her to complete a drug screening before returning to work.

She told a company representative that she would “fail” the test because she was a registered marijuana user, the release said. When she did in fact test positive for marijuana, she was told she would not be allowed to continue her employment with Adecco.

“Using medical marijuana would never have gotten in the way of me doing my job, because I never would have taken it while on duty,” Thomas said in the release. “I choose to use medical marijuana to control my pain because it doesn’t have any of the side effects of stronger pain medication, like addiction. The incredible thing is, if I was using a stronger drug, I could have kept my job.”

The lawsuit seeks damages from Adecco, including back wages and reinstatement.