The California Supreme Court on Wednesday denied a last-minute challenge to a pending state law that opens police records to the public and eases what currently is one of the nation’s most secretive police privacy laws.

The justices denied a police union’s petition contending that the law should make public police records only for incidents that happen after the law took effect Tuesday. They gave no explanation for the one-line denial order.

The law was passed in response to national distress over a series of fatal police shootings of unarmed minority men, but applies only when officers are found to have improperly used force or discharged firearms, committed sexual assaults on the job, or have been dishonest in official duties.

The San Bernardino County sheriff’s deputies union asked the justices to find that the law should only apply to incidents in 2019 or later. The law “contains no legislative direction for a retroactive application,” according to the petition.

It also cites a letter from Los Angeles police Chief Michel Moore saying that applying the law to older incidents could cost his law enforcement department hundreds of thousands of work hours. The LAPD is expecting “a massive influx in historical records requests” and hiring extra employees and buying expensive hardware and software to comply, Moore wrote.

Attorneys for the union did not immediately respond to a request for comment.

Peter Bibring, the American Civil Liberties Union’s director of police practices for California, called the union’s legal arguments “meritless.”

The bill’s author and advocates including some media organizations said legislators clearly intended the law to include any records, no matter how old.

By signing the bill, termed-out Democratic Gov. Jerry Brown partially reversed his approval 40 years ago of a law imposing some of the nation’s toughest law enforcement secrecy rules.

David Snyder, executive director of the pro-transparency First Amendment Coalition, said it was unusual for the union to appeal directly to the state Supreme Court instead of starting with a county superior court.

Media organizations including the Los Angeles Times, radio station KQED and the California News Publishers Association joined the coalition in opposing the union’s challenge.

Organizations representing cities, counties, sheriffs and police chiefs had not taken a position on the union’s challenge. None were aware of other agencies following the lead of Inglewood, where city council members recently voted to destroy old police shooting and internal investigation records.

“It’s the first time in 40 years that California opened up the secrecy around police records,” said the new law’s author, Democratic state Sen. Nancy Skinner of Berkeley.She added: “Good policing requires community trust, and one way to build that trust is transparency.”