Saco, Maine ? Carleen Simpson planned carefully for a retirement that would allow her to travel, including regular trips north of the border for cheaper prescription drugs.

On her first trip, she saved enough money to heat her house for a year.

“I used to worry about being a little old lady eating dog food so I could pay for my prescriptions,” Simpson said. “That’s a sad situation when you’re living in a country that’s so wealthy.”

Maine legislators passed a groundbreaking law designed to lower drug prices for state residents without insurance coverage, but a drug industry legal challenge has blocked it from going into effect. On Wednesday, the U.S. Supreme Court will hear arguments on an appeal.

The Maine Rx law, enacted in 2000, would let the state negotiate for lower prices on behalf of more than 300,000 residents who pay for prescription drugs.

If prices didn’t drop in three years, the state could impose price controls.

Twenty-nine states and Puerto Rico filed a joint brief in support Maine’s position. Kansas was not among the states; Missouri and Oklahoma were.

For states, Maine Rx is attractive because it doesn’t require federal approval and it costs taxpayers little.

The Pharmaceutical Research and Manufacturers of America, which sued to overturn Maine Rx, contends the law is unconstitutional because it regulates interstate commerce and runs afoul of Medicaid law.

The Supreme Court will hear a three-sided argument Wednesday with lawyers for the state and the drug industry opposing each other, and the Bush administration staking out middle ground by arguing that Maine Rx would be legal if restricted to low-income Mainers instead of being made widely available.

After Maine Rx was put on hold, the state obtained a Medicaid waiver to create the Healthy Maine prescriptions program to give discounts to more than 100,000 residents.

But that, too, was blocked. The Court of Appeals for the District of Columbia ruled that the Healthy Maine Prescriptions program, like a similar measure struck down in Vermont, illegally expanded the Medicaid program.

The pharmaceutical industry has been vilified for fighting Maine Rx by critics who say it is concerned about profits.

But Jeff Trewitt, a spokesman for the trade group, said drug manufacturers are obligated to challenge a law they believe puts politicians in charge of the drugs available to patients.

Simpson, 66, expects to save $2,000 this year by traveling 240 miles to get her drugs in Canada.

Prescription drugs are cheaper in Canada largely because of government caps on drug prices there. Federal regulations in the United States allow travelers to bring in a 90-day personal supply.