“The Wall Street Journal” (http://macte.ch/TZROb) reports the U.S. Department of Justice is investigating whether Samsung has misused some of its mobile-device patents in ways that violate antitrust law, rival Apple said in a legal document filed late Monday.

The department is purportedly investigating Samsung’s use of patents that are deemed essential to wireless technology. The Justice Department hasn’t commented on the matter.

The European Union’s European Commission launched launched a formal investigation in January looking into whether Samsung was using its essential wireless patents as an anticompetitive too. If so, this would violate a commitment the company made to the European Telecommunications Standards Institute.