The long-running battle between Boston Scientific Corp. (NYSE:BSX) and Johnson & Johnson’s (NYSE:JNJ) Cordis Corp. over coronary stent patents went another round this week when a federal judge ruled that Cordis infringes a BSX patent.

Judge Susan Robinson of the U.S. District Court for Delaware granted the Natick, Mass.-based catheter pioneer’s move for summary judgment of infringement and denied a Cordis motion to delay the jury trial phase of the case, slated to begin May 5.

The case involves 2.25mm stents — Cordis and BSX make the only such models available in the U.S. Cordis and Boston Scientific sued each other in early 2003, each alleging patent infringement. A jury ruled for BSX, finding that Cordis’ Cypher and BX Velocity stents wre in violation of the patent. The decision was upheld on appeal, with the damages portion set to be decided by a jury next month (a settlement allows Cordis to make the stents pending the outcome of the case).

Things swung the other way in February, when a federal judge in New Jersey dealt a blow to Boston Scientific and Abbott Laboratories (NYSE:ABT) in their patent war with Cordis and Pfizer Inc. (NYSE:PFE) subsidiary Wyeth. BSX and Abbott had moved to stay the lawsuit, filed in September 2009 by Cordis and Wyeth over drug-eluting stent technology, pending a review by the U.S. Patent and Trademark Office. But Judge Joel Pisano denied the motion, ruling that the USPTO review — which one expert witness said could take more than six years — would unfairly disadvantage Cordis.

And BSX bit the bullet on a slew of other cases, agreeing to settle them for $716 million back in September 2009.