The estate of Dr. Michel Mirowski, who helped invent the implantable defibrillator owes Medtronic (NYSE:MDT) $6 million to cover legal fees in their long-running patent spat, a federal appeals court ruled today.

Mirowski Family Ventures represents the estate of CRM pioneer Dr. Michel Mirowski. The group, which controls several patents related to ICDs and cardiac resynchronization therapy devices, has been pursuing patent infringement cases against Medtronic, Guidant and successor Boston Scientific (NYSE:BSX) for years.

The case, which eventually found its way to the U.S. Supreme Court, dates its origins back to the early 1970s, when Mirowski licensed the patents to Eli Lilly (NYSE:LLY), then Medtronic’s main CRM competitor. (In 2004 the licenses passed to Lilly subsidiary Guidant, which Boston acquired in 2006.) In 2011, Judge Susan Robinson of the U.S. District Court for Delaware agreed with Medtronic’s bid to invalidate 1 of the patents; in 2015, after several rounds of appeals, Robinson ordered MFV to put up about $6 million to cover Medtronic’s legal fees.

MFV asked the U.S. Court of Appeals for the Federal Circuit to overturn that decision, arguing that its deal with Eli Lilly and later Guidant shouldn’t apply. If found liable for the fees, MFV argued, Boston Scientific and Guidant should also be found liable.

The Federal Circuit upheld the lower court’s judgment, ruling that the MFV-Lilly deal obligated the estate to cover Medtronic’s tab.

“We construe the legal effect of the [MFV-Lilly deal] to be that Mirowski Family Ventures assumed both Eli Lilly’s right to assert infringement against Medtronic and Eli Lilly’s obligation to pay Medtronic’s attorney fees if Medtronic was deemed the winning party in any resulting litigation. Therefore, the district court did not err in finding that Mirowski Family Ventures was bound by the fee shifting provision of the 1991 Agreement,” Judge Jimmie Reyna wrote for the appeals court.