Washington seems to be in the grip of hyperpartisan gridlock these days. Important bills are passed on party-line votes (when they are passed at all) and the investigative committees of Congress appear to be sideshows, unable to agree on basic facts.

Many Americans despair that Republicans and Democrats seem incapable of coming together to do anything important.

Take heart — the two parties just did do something big together. On Wednesday, President Trump will sign into law the Stop Enabling Sex Traffickers Act, a bill designed to crack down on websites that knowingly facilitate the online sex trafficking of vulnerable persons, including underage boys and girls. And the FBI, informed by evidence collected during a nearly two-year bipartisan investigation by the Senate’s Permanent Subcommittee on Investigations, just seized the website Backpage.com – which the Center for Missing and Exploited Children says is responsible for 73 percent of the 10,000 child sex trafficking reports in receives each year – and arrested seven of its top executives.

You might think cracking down on child sex traffickers would be a legislative layup. You’d be wrong. The bill — authored by Republican Sens. Rob Portman (Ohio), John McCain (Ariz.), and John Cornyn (Tex.) and Democrats Richard Blumenthal (Conn.) Claire McCaskill (Mo.) and Heidi Heitkamp (N.D.) — was hard to pass. (Full disclosure: My wife works for Portman).

The act faced a wall of opposition from Silicon Valley because it amended Section 230 of the Communications Decency Act, which gave blanket immunity to online entities that publish third-party content from civil and criminal prosecution. Big Tech wanted to preserve that blanket immunity, even if it gave legal cover to websites that were using it to sell children for sex. When child sex trafficking survivors tried to sue Backpage, and state attorneys general tried to prosecute the owners, federal courts ruled against them, specifically citing Section 230. This did not move Big Tech. Chief among the culprits was Google, which apparently forgot its old corporate motto of “Don’t Be Evil” and lobbied fiercely against the bill.

How did the senators overcome Big Tech’s lobbying campaign? First Portman and McCaskill, the chairman and ranking member of the permanent subcommittee on investigations, used their subpoena power to gather corporate files, bank records, and other evidence that Backpage knowingly facilitated criminal sex trafficking of vulnerable women and children, and then covered up that evidence. They fought Backpage all the way to the Supreme Court to enforce their subpoenas. The subcommittee then published a voluminous report detailing its findings of their 20-month investigation, including evidence that Backpage knew it was facilitating child sex trafficking and that it was not simply a passive publisher of third-party content. Instead the company was automatically editing users’ child sex ads to strip them of words that might arouse suspicion (such as “lolita,” “teenage,” “rape,” “young,” “amber alert,” “little girl,” “fresh,” “innocent” and “school girl”) before publishing them and advised users on how to create “clean” postings.

Then Portman, McCaskill and their co-authors used the result of their investigation to craft a narrow legislative fix that would allow bad actors such as Backpage to be held accountable. The bill they produced allows sex trafficking victims to sue the websites that facilitated the crimes against them and allows state law enforcement officials, not just the Justice Department, to prosecute websites that violate federal sex trafficking laws. The committee also turned over all its raw documents to the Justice Department last summer, urging them to undertake a criminal review, which Justice did.

Despite all the Silicon Valley money against them, the senators never wavered. Through the sheer power of the testimony of trafficking survivors, Mary Mazzio’s documentary “I am Jane Doe,” the evidence of crimes committed by Backpage, and the support of law enforcement, anti-trafficking advocates, 50 state attorneys general, the civil rights community and faith-based groups — as well as carefully negotiated language — they wore down most of Big Tech’s opposition. Last November, Facebook finally came on board. But Google shamefully never relented in its opposition. Despite this, the act overwhelmingly passed both chambers of Congress.

Thanks to this bipartisan effort, the world’s largest online child sex bazaar is shuttered, many of its executives are under indictment and sex trafficking victims can finally get justice in court. These senators have given hope not just to the survivors but also to millions of Americans who had lost faith that their elected leaders could put aside partisanship and resist the power of money in politics for the good of the country.

Follow Marc A. Thiessen on Twitter, @marcthiessen.