A new one on me, but they brought a pre-emptive lawsuit against the Gayes and Bridgeport Music, who owned the rights to Funkadelic's "Sexy Ways", which also influenced Blurred Lines. Was this a case of getting the first punch in? Seems like a bad move to me, as it's like an admission of guilt. We haven't ripped off your music, and we want you to admit we haven't before you try to prove we have. Only in America.
Incidentally, George Clinton has gone on record as saying that "Sexy Ways" hasn't been ripped off.