By Diane Bartz WASHINGTON (Reuters) – A U.S. House of Representatives subcommittee on Thursday approved a draft bill aimed at reining in companies that seek licensing fees for invalid patents or are otherwise dishonest in writing what are known as “demand letters.” The Energy and Commerce Committee subcommittee on Commerce, Manufacturing and Trade voted 13-6 to approve a draft of the Targeting Rogue and Opaque Letters Act, or TROL Act. The bill has provoked controversy because it would allow the Federal Trade Commission to pursue companies that are dishonest in demanding licensing for patents but only if it can prove bad faith – essentially making it more difficult for the agency. Lawmakers have made several attempts to tackle frivolous patent litigation, which has recently moved from the tech and pharmaceutical sectors into areas such as retailing, where patent fights had been nearly unknown. The bill’s stated goal is to attack the practice by some companies which, critics say, write letters demanding licensing fees without first establishing that infringement exists or disclosing who owns the patent.