Kayden Kross, pictured here, was one of the plaintiffs challenging Measure B. Associated Press In a ruling late Friday, a California federal judge found that Los Angeles County can enforce a voter-approved rule requiring porn actors to wear condoms during filming.

Judge Dean Pregerson refused to grant a preliminary injunction in the case — which would have put the rule on hold while porn-makers challenged it — because he predicted they would lose their suit claiming Measure B violated their free speech rights.

"Because Plaintiffs' First Amendment claim regarding Measure B's condom requirement is unlikely to succeed on the merits, the court DENIES a preliminary injunction on the issue," he wrote.

The decision is a big setback to two porn-makers and two porn actors who sued the county of Los Angeles to stop it from enacting Measure B, also known as the Los Angeles County Safer Sex in the Adult Film Industry Act.

Opponents of Measure B, including the porn industry, claimed the rule violated their free speech rights under the First Amendment. They also predicted the voter-approved measure would hurt California's economy by spurring porn-makers to shoot condom-free movies in other states.

In challenging Measure B, porn groups said the condom rule wasn't necessary because porn actors got tested regularly for STDs. Judge Pregerson said they didn't do a great job of proving that point, though.

The groups "presented evidence from individuals in the adult film industry, but not in the public health or medical profession, who claim testing is so effective and universal that condoms are unnecessary," he writes.