Hewlett-Packard said that a US federal agency has backed its claim that rival MicroJet Technology Co. was infringing on patents for lucrative inkjet printer cartridges. The International Trade Commission issued a favorable \"initial determination\" regarding the validity of HP\'s patents in the case, according to the California-based computer and printer maker. HP on Friday said the ITC ruled that MicroJet infringed on HP patents while Asia Pacific Microsystems was a \"contributory infringer.\" \"HP is pleased with the outcome on these matters and the ITC\'s pursuit of legal enforcement against practices that violate intellectual property rights,\" said HP executive Andy Binder. The decision was reportedly based on the quasi-judicial federal agency\'s investigation of a complaint filed a year ago about importation of printer cartridges featuring HP\'s patented technology.