The law, , seeks to limit the sexual exploitation of minors by making it a felony to run advertisements for such services. It requires online advertising platforms to attempt to verify in person the age of people whose sexual services are advertised.

The legislation was signed into law by Washington Governor Christine Gregoire on March 29 and was set to take effect last week. Its enforcement has been delayed as the result of a legal challenge from the online classifieds site, Backpage.com, which is owned by Village Voice Media. Backpage.com has the state and county attorneys general in federal court.

EFF filed a on Thursday seeking to intervene in the case on behalf of , a digital library that archives Web content.

Both Backpage and Internet Archive assert in their filings that they do not condone underage prostitution, but they argue that the law should not punish online service providers.

"At its core, this lawsuit is about the ability of the state of Washington to impose liability on online service providers for hosting and disseminating content created by third parties," the Internet Archive motion reads.