Online want ad titan Craigslist never before this month hired lobbyists in Washington, D.C. This is despite founder Craig Newmark being a long-time, outspoken proponent of net neutrality and Craigslist having a vested interest net neutrality proposals opposed by Internet service providers, and a long-running war over net neutrality having played out over successive administrations.

But something has now caused Craigslist to ditch its “no lobbyists” stance: An anti-sex trafficking bill pushed by Sen. Rob Portman. Via Politico:

CRAIGSLIST HIRES ITS FIRST LOBBYISTS: Craigslist has hired former Rep. Rick Boucher (D-Va.) and four of his colleagues at Sidley Austin to lobby on an anti-sex trafficking bill. The bill, championed by Sens. Rob Portman (R-Ohio) and Richard Blumenthal (D-Conn.), has attracted fierce opposition from Silicon Valley because it would change a law that protects websites from lawsuits over content posted by users. It’s the first time Craigslist has hired a lobbying firm.

The most high-profile opponent of Portman’s legislation has been Google, which funded opposition to Portman’s bill. However, other major names in Silicon Valley, principally content companies, also oppose the bill.

Now that list apparently includes Craigslist, which is presumably worried about liability where a pimp of underage girls (or boys) posts ads offering sex services on the site and where the site therefore contributes, albeit in an unintentional manner, to sex trafficking and exploitation– a situation that would presumably occur where Craigslist personnel were failing to police ads and take down objectionable content.