Zen Magnets, a Denver company that has been locked for four years in a battle with the federal government, scored a major victory last week with a 10th Circuit Court of Appeals ruling that will allow it to resume selling sets of BB-sized magnets intended to be used for molding together in sculptures or artistic designs.

The U.S. Consumer Product Safety Commission maintains that the powerful rare-earth magnets, like those marketed by Zen Magnets, are dangerous and still should not be sold.

Small, magnetic balls have been the crosshairs of the CPSC for more than a decade. The federal regulatory agency says that from 2009 to 2014, more than 100 cases were reported to the CPSC involving children swallowing two or more magnets from these sets and injuring themselves in the process. In some cases, magnets connected inside their bodies which tore through tissue, causing internal bleeding and injuries to vital organs. There was one fatality reported, in 2013. The agency’s National Electronic Injury Surveillance System estimates there could have been about 2,900 cases during the same five-year period.

But Zen Magnets founder Shihan Qu, a University of Colorado graduate, says the CPSC’s estimates are inflated and are based on a definition too broad to isolate just his magnet spheres.

In 2012, the agency sent letters to 13 companies that sold the magnets, asking them to stop distributing them. Most of companies complied, but Zen Magnets and two others pushed back.

As the agency increased its effort to get the magnets off the market, companies started dropping off and soon Zen was the last distributor standing. The company was later sued for selling a recalled item — 917,000 magnets they bought from a New Jersey company that was offloading inventory under CPSC orders. Qu said Zen settled that case.

The Nov. 22 ruling overturns the 2014 CPSC ban of magnet sets, allowing Zen to import, manufacture and sell the magnet sets again. But the business remains in limbo: CPSC can still file a motion for the court to reconsider its opinion.

“At this moment, the commission is considering its options going forward,” agency spokesman Scott Wolfson said. “What doesn’t change is our perspective. This is a deadly risk to not only young children, but also tweens and teens.”

Qu’s attorney David C. Japha sees this as a profound victory for Zen and small businesses in general. He said he’s done extensive research and found a circuit court hasn’t overturned a CPSC ruling since 1983. Japha explained that Zen’s victory directly challenges the federal agency’s ability to determine how to enact regulations and the statutes.

When the CPSC enacts regulations, the court explained in its opinion, it has to conduct a cost-benefit analysis on the product. It has to weigh the potential injury a product can cause and the likelihood of that happening against the harm the regulation will pose to manufacturers.

The CPSC analysis neglected to address critical ambiguities, the judges wrote, including “the degree of the risk of injury caused by magnet sets,” and “the public’s need for the sets and the rule’s effect on their utility and availability.”

Japha also argued that the agency underplayed the educational value of the magnets.

“They didn’t consider the education benefits of this project: physics chemistry, anatomy, biology. One teacher from California testified they could show how enzymes work in the body,” he said.

Qu said that the analysis of the financial impact of regulation neglected to account for the fact that the agency had already gutted the industry.

“In reality they already killed most of the market and the analysis of their ban was unrepresentative of the current market because of their enforcement,” he said. “The cost-benefit analysis was there were 13 companies, when there was just us fighting.”

The court also said that the agency relied on statistics from a time period before regulations stifled the industry. Those numbers were no longer accurate enough to justify further regulation.