Just weeks after a jury ruled that defibrillator rivals Zoll Medical and Philips (NYSE:PHG) each infringed on one another’s intellectual property, Zoll is looking to take the battle back to court with a new complaint filed in Massachusetts.

Zoll claimed that Philips’ HeartStart XL external hospital-use defibrillators infringe on a patent for "semiautomatic defibrillator with heart rate alarm driven by shock advisory algorithm," which is already involved in another legal dispute between the companies.

The rivals have been fighting over their AED patents for nearly 4 years. Philips, the Dutch conglomerate whose healthcare division is based in Andover, Mass., sued its neighbor in nearby Chelmsford in June 2010, alleging infringement of 15 AED patents. Zoll countered with a lawsuit of its own a month later, accusing Philips of infringing 5 Zoll AED patents. The cases were later consolidated and scheduled for trial last month, according to court documents.

The medical device companies filed a series of motions for summary judgment in the U.S. District Court for Massachusetts, but Judge Nathaniel Gorton in November 2013 denied all of them except a joint motion to nix certain claims, driving the case to a jury trial.

The December trial resulted in wins and losses for both parties, with a jury ruling that Zoll infringed 4 Philips patents and that Philips infringed 2 Zoll patents, Law360.com reported.

The newest complaint involves Zoll patent 5,391,187 and Philips’ HeartStart XL hospital defibrillators, which can be operated manually or with voice-guided automation.