In what seems like a never-ending string of patent lawsuits among smartphone manufacturers, Apple has accused HTC of violating FRAND and antitrust regulations regarding what it claims are essential 4G/LTE technology-related patents.

The suit, filed in a Virginia court, is made up of counterclaims to HTC's International Trade Commission complaints against Apple.

Apple is arguing that the nature of three patents, which HTC bought from ADC Telecommunications and claimed in a previous suit were standard-essential, should have been "disclosed by HTC and ADC to the relevant standards setting organizations ('SSOs'), and commitments to license on fair, reasonable and nondiscriminatory terms ('FRAND') should have been made for their purported inclusion in standards and in evolving standards under development."

Instead, Apple alleges, "HTC and ADC have conspired to conceal from the SSOs the existence of the ADC patents and have purposefully evaded any obligations to license under FRAND terms." Accordingly, the suit focusses on HTC's alleged abuse of antitrust and monopoly regulation, as well as fraud.

Apple has also filed similar counterclaims against Samsung and Motorola, suggesting that standard-essential patents could prove to be a new legal strategy employed by mobile companies to compete against one another.