A US-based doctor has filed a lawsuit against Apple, claiming that the company engaged in willful patent violation. The issue at hand is that the Apple Watch Series 3 allegedly violates a patent filed by Dr Joseph Wiesel with regards to atrial fibrillation (AFib) detection technology.

According to New York University cardiologist Dr. Joseph Wiesel, his patent was a “pioneering step” toward being able to successfully detect AFib. AFib can lead to blood clots, stroke, heart failure, and other issues. The American Heart Association notes that untreated AFib typically doubles one’s chance of heart-related death.

According to Dr Joseph Wiesel, he was originally awarded a patent which describes how to monitor “irregular pulse rhythms from a succession of time intervals” on March 28, 2006, which allows patients to use “photoplethysmography” — used in the Apple Watch with green light and sensors.

Dr Joseph Wiesel first contacted Apple in September 2017, giving the Cupertino, California-based company detailed information about the patent but apparently was rejected. In his lawsuit, Wiesel is asking the court to block the Cupertino company from using the technology and also for royalties he believed was owed to him.