A federal judge announced Thursday that he’s temporarily blocking a new California law aimed at releasing President Donald Trump’s tax returns, several outlets reported.

Democratic Gov. Gavin Newsomsigned the bill into law in July. It requires presidential candidates to release their tax returns from the last five years in order to appear on the California primary ballot. Both the Trump campaign and the GOP sued the state over the law’s constitutionality.

U.S. District Judge Morrison England Jr. issued the temporary injunction from the bench, saying he will make a final ruling in the coming days but that Trump and other candidates could face “irreparable harm without temporary relief.”

Trump is the first president in four decades to not release his tax returns, which could shed important light on his financial dealings and conflicts of interest.

Though the first-of-its-kind law is controversial even among Democrats, Newsom defended his decision to sign it as a necessary response to an unprecedented situation.

“These are extraordinary times and states have a legal and moral duty to do everything in their power to ensure leaders seeking the highest offices meet minimal standards, and to restore public confidence,” he said in July. “The disclosure required by this bill will shed light on conflicts of interest, self-dealing, or influence from domestic and foreign business interest.”

Newsom’s predecessor, Gov. Jerry Brown, vetoed a similar bill in 2017, saying he’s wary to “start down a road that well might lead to an ever-escalating set of differing state requirements for presidential candidates.”

All leading candidates for the Democratic presidential nominee have released their tax returns.