Today's ruling, from US District Court Judge Ricardo S. Martinez, doesn't mean that Backpage.com has won its case against Washington State's new law to rein in underage sex trafficking. The website, which is owned by Village Voice Media LLC—owners of the Seattle Weekly—has simply improved on June's temporary restraining order with a preliminary injunction.

Still, it's an important step in what should be an interesting legal process.

At issue is a new Washington law that essentially requires any publication running escort ads to obtain a government-issued ID from the person being advertised, in order to ensure he or she is not underage.

Judge Martinez says he granted the preliminary injunction, in part, because of the potential First Amendment issues involved in regulating advertising in this manner:

Having shown a likelihood of success on the merits, Plaintiffs adequately satisfy the remaining elements for securing a preliminary injunction: irreparable harm, that the balance of equities tips in their favor, and that an injunction would be in the public interest. See Winter, 555 U.S. at 24. First, “[t]he loss of First Amendment freedoms for even minimal periods of time, unquestionably constitutes irreparable injury.”

That's not to say Judge Martinez agrees that Washington's new law violates the First Amendment. Just that Backpage.com has shown that it may well be able to prove in court that it does, so for now the most prudent course is to suspend the law.