Mt. Gox has been contacted by Coinlab (US) regarding a formal complaint filed against us in the United States. As we have just now received the complaint, neither Mt. Gox nor our legal team can make any official comment on the matter at this time, but we take this very seriously and will respond appropriately and quickly once we have had time to review it.

Source:
https://mtgox.com/pdf/20130503_coinlab_lawsuit.pdf