The lawsuit alleges that Ethicon’s latest ultrasonic surgical product, the Harmonic ACE+7, infringes three Covidien patents. The same federal court found that these patents were valid and had been infringed in an earlier lawsuit relating to other Ethicon ultrasonic surgical products.

Covidien Surgical Solutions vice president and general counsel Lawrence Weiss said: "The federal court in Connecticut has previously recognized the value of Covidien’s intellectual property in this area and, with this new lawsuit, we will continue to vigorously protect both our innovations and intellectual property."

The lawsuit contends that US Patents 6,063,050; 6,468,286; and 6,682,544 are infringed by Ethicon’s Harmonic ACE+7 Shears.

Ethicon’s Harmonic devices were found to infringe the same patents in a prior suit in the same court that resulted in a damages award against Ethicon of more than $175m, a finding that is currently under appeal.

The new suit asks the court to enjoin Ethicon from continuing to make and sell the Harmonic ACE+7 device and to grant damages for the patent infringement.