(AP) – Horse racing’s new anti-doping program was dealt a blow Friday when a judge in Texas ordered the Horseracing Integrity and Safety Authority to stop enforcing its rules involving medications and illegal drugs until May 1.

Judge James Wesley Hendrix of the U.S. District Court for the Northern District of Texas issued a 30-day injunction in response to a request for an emergency injunction by the National Horsemen’s Benevolent and Protective Association and the state of Texas.

The two groups filed their request Monday, the same day HISA began enforcing its new anti-doping and medication rules in states where live racing is currently going on.

In the filing, the plaintiffs had asked Hendrix to rule in an expedited manner on the request, noting that the Florida Derby and Arkansas Derby — major preps for the Kentucky Derby — are to be run Saturday.

“The plaintiffs have shown a serious risk of harm — potential physical injury to racehorses, potential disqualification from Triple Crown prep races, and the burden of coming into compliance with a new anti-doping regulatory scheme without the legally required delayed effective date,” Hendrix wrote.

The plaintiffs argued that typically there’s a 30-day waiting period before implementing new rules. Hendrix wrote that those procedures should have applied to HISA’s enforcement.

Lisa Lazarus, CEO of HISA, said the group would accept the judge’s ruling and not appeal it, according to the Daily Racing Form.

As a result, the affected states will resume responsibility for their respective anti-doping programs.

HISA has faced resistance from various factions in horse racing since it was created by federal legislation in 2020 to be the sport’s first national regulator. Previously, the 38 U.S. racing states have operated under their own patchwork set of rules.