Berkshire Hathaway's Brooks Sports has filed a lawsuit against German shoemaker Puma in the Virginia federal court. The lawsuit is part of the latest salvo in an ongoing intellectual property dispute between the two companies. Brooks Sports claims that Puma has threatened to sue it for allegedly infringing on a patent related to a type of ridged shoe sole. Brooks is seeking a court ruling that its Glycerin running shoes do not violate Puma's patent rights.