Craiglist doesn't need to write those posts. Under their TOS, Craiglist has a license to the posts (which are copyrighted by their owners ). This license gives Craiglist the authority to enforce copyright against persons who interfere with Craigslists' license in the posts. Thus, the last sentence of their TOS is perfectly legal and enforceable. The license would not give Craiglist a license to do anything to other services on which the original posters also post their listings to. But that is not the case here.