Craigslist has hired prominent Washington-D.C. law firm Sidley Austin to advocate on Capitol Hill against a new bill that aims to fight sex trafficking by going after the websites and other online platforms that publish third-party advertisements for sex acts.

The San Francisco-based online ad giant, which is infamous for its “personals” classifieds forums along with sites like Backpage.com, has retained Sidley Austin in response to S. 1693, or “The Stop Enabling Sex Traffickers Act.” That bill would amend the federal criminal code and allow the government to press charges against websites that knowingly allow the promotion of sex trafficking. It would also allow users to potentially sue those sites.

S. 1693 was introduced in August by Sen. Rob Portman (R-OH). It currently has 54 co-sponsors. A House version of the bill, H.R. 1865, or the “Allow States and Victims to Fight Online Sex Trafficking Act of 2017,” was introduced in April by Rep. Ann Wagner (R-MO).

Senator Rob Portman (R-Oh).Senator Rob Portman (R-OH).

Critics of the bill claim that making websites criminally or civilly liable for content posted by third parties sets a dangerous legal precedent, potentially putting Internet businesses or platforms in jeopardy while not doing anything to actually punish sex traffickers.

Currently, the Communications Decency Act, which was passed in 1996, prohibits Internet publishers or service providers from being legally responsible for content posted by its users. The ACLU and Internet advocacy group the Electronic Frontier Foundation are among organizations that have recently expressed disapproval of S. 1693.

A five-person team at Sidley Austin handles the account, including Rick Boucher, who was formerly U.S. Rep. to Virginia’s 9th district; Dora Hughes, former health policy advisor to then-Senator Barack Obama (D-IL) and deputy director for the Committee on Health, Education, Labor, & Pensions in the U.S. Senate under Senator Edward Kennedy (D-MA); Patricia DeLoatche, former health policy director to Senator Orrin Hatch (R-UT); Laura Cohen, former intern at the Health Subcommittee in the Energy and Commerce Committee; and Michael Borden, former legislative aide to Rep. Jim Leach (R-IA).

Sidley Austin is one of the largest corporate law firms in the U.S., with nearly 2,000 attorneys and annual revenues of more than one billion.