The U.S. Justice Department is investigating an antitrust case involving South Korea’s Samsung Electronics over suspicions it abused standard-essential patents.

Software patent-news blog Foss Patents reports Apple said in a filing with the U.S.’ International Trade Commission on its patent suit against Samsung that the Justice Department opened an investigation regarding the manner in which Samsung used or misused its declared-essential patents.

The blog confirmed that Apple’s representation is accurate. A relevant passage from the filing was posted on the blog.