On Friday, federal regulators announced that they are launching an investigation into wearable monitoring devices, including Fitbit and Garmin, after rival company, Philips, accused the companies of patent violations, as first reported by Reuters.

In a statement, the US International Trade Commission (USITC) confirmed that its investigation into two of the most popular wearable companies was prompted by a complaint filed by the Philips company last month. The USITC said other wearable companies, including two based in China, were also under investigation.

“The USITC has not yet made any decision on the merits of the case,” the statement reads. “The USITC will make a final determination in the investigation at the earliest practicable time.”

The case centers on four patents owned by Philips, which cover a range of smartwatch functions, including motion tracking and alarm reporting among other functions. “We believe these claims are without merit and a result of Philips’s failure to succeed in the wearables market,” a Fitbit spokesperson told The Verge. Garmin declined to comment.

“We believe these claims are without merit and a result of Philips’s failure to succeed in the wearables market”

A Philips spokesperson said that the company had attempted to negotiate licensing agreements with Fitbit and Garmin for three years, but talks ultimately broke down. “Philips expects third parties to respect Philips’ intellectual property in the same way as Philips respects the intellectual property rights of third parties,” the spokesperson said.

All three companies compete in the wearable health-monitoring market, and Fitbit and Garmin’s products are far more successful than the Philips Health Watch. In its December complaint, Netherlands-based Philips and its North American counterpart requested that regulators implement tariffs or an import ban on any companies found to infringe the company’s patents or intellectual property.