Minnesota is one of several states to adopt or consider legislation to make insulin more affordable. (AMBER FORD, New York Times/The Minnesota Star Tribune)

A federal appeals court on Monday revived a lawsuit filed by the country's biggest pharmaceutical manufacturers that sought to end the state's insulin safety net program.

On the day in 2020 that a state law took effect requiring drug companies to provide insulin in emergency situations to those who can't afford it, the Pharmaceutical Research and Manufacturers of America, or PhRMA, filed suit in U.S. District Court.

In a lawsuit filed on behalf of three of the country's biggest drug makers — Eli Lilly and Co., Novo Nordisk Inc., and Sanofi — PhRMA claimed that the program violated clauses in the U.S. Constitution prohibiting the state from taking property for public use without compensation.

They argued that the state of Minnesota forced insulin manufacturers to give their products to residents for free when they already offer alternatives to help people with diabetes.

U.S. District Judge David Doty dismissed the lawsuit in March 2021, citing a lack of standing and saying that the case should be heard in state court. PhRMA then appealed to the Eighth U.S. Circuit Court of Appeals.

The drugmakers argued that state law only allows for compensation for taking property for public use once that action had been completed. The insulin safety net program, they argued, authorized a "repetitive (and essentially endless) series" of their property being taken for such use, in turn requiring new lawsuits to seek compensation.

"Forcing a party to engage in repetitive lawsuits indefinitely seems to be precisely the sort of legal inadequacy that would make equitable relief an available and preferred method of redress," Chief Judge Lavenski Smith wrote in a Monday opinion.

Priscilla VanderVeer, a spokesperson for PhRMA, said Monday that the group was confident that it would prevail in district court.

"We remain willing to work with state officials to develop lawful means of revising the system that currently stands in the way of common-sense solutions to help patients afford their medicines," VanderVeer said.

The Minnesota Attorney General's Office is representing the state Board of Pharmacy in the lawsuit. John Stiles, a spokesperson for the office, said Monday that "we are reviewing the decision, but it's important to note the court did not rule on the merits of the law or enjoin it."

Staff writer Briana Bierschbach contributed to this report.