A federal judge has overturned Maine’s first-in-the-nation law allowing residents to purchase medication by mail from other countries.

U.S. Chief District Judge Nancy Torresen’s ruling Monday comes more than a year after several Maine pharmacy groups filed suit against the state over the 2013 law, arguing it jeopardizes the safety of the nation’s prescription drug supply and opens the door to counterfeit and tainted medications.

Federal law strictly limits the importing of prescription drugs from foreign countries for personal use. Torresen ruled that Maine infringed on the federal government’s established regulatory authority by allowing drug importation at the state level. Her decision nullifies the law, pending a potential appeal by the state.

The three pharmacy groups argued Maine’s law sidestepped the U.S. Food and Drug Administration’s oversight, designed to protect consumers from unsafe medications. Their suit, filed in September 2013, names as defendants Maine Attorney General Janet Mills and Richard Rosen, who has since been named the state’s finance commissioner.

“Maine pharmacists are relieved that Judge Torresen’s ruling ensures the safety of prescription drugs for Mainers by upholding federal laws that are designed to prevent unapproved and substandard drugs from coming into the United States,” said Kenneth McCall, immediate past president of the Maine Pharmacy Association, one of the plaintiffs in the case.

His group was joined by the Maine Society of Health System Pharmacists and the Retail Association of Maine. The drug industry’s largest lobbying group, the Pharmaceutical Research and Manufacturers of America, also sued the state, but Torreson dismissed the organization as a plaintiff in June 2014.

“Maine people can be assured that the prescriptions that are filled by Maine pharmacists are approved medications,” said Curtis Picard of the Retail Association of Maine. “We expect foreign companies to abide by this ruling and federal law and to cease illegally importing drugs into Maine.”

Maine Attorney General Janet Mills said the issue of drug importation needs further scrutiny, but did not indicate whether she plans to appeal Monday’s decision.

“Congress and the FDA should re-examine their policy towards importation of prescription drugs,” she said in a statement. “Meanwhile, we will review the decision and decide on next steps.”

When Maine passed its law in June 2013, the state became the first in the nation to formally defy federal regulations prohibiting U.S. residents from importing drugs through foreign pharmacies, which often sell the same medications for half the cost.

While Maine’s law set a new national precedent, the controversial legislation unofficially sanctioned a hunt for cheaper prescription drugs that has driven Mainers across the border to Canada for years.

The law allowed Maine residents to buy prescription drugs from Internet pharmacies in Canada, the U.K., Australia and New Zealand, which the U.S. government deems to have equivalent or greater drug safety and licensing regulations. Those countries, among others, can sell prescription drugs more cheaply because their governments cap prices or negotiate prices with drug makers.

Supporters of the law, including former Maine Sen. Troy Jackson, have argued that drugs from those countries are safe and that consumers are being held hostage by high drug prices charged by American pharmacies. Maine’s law put the federal government on the spot over the issue of unaffordable prescription medications, he said in January.

“The pharmacy industry is pushing hard to stop this because they see their cash cow possibly slipping away,” Jackson said.

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