The U.S. Supreme Court has declined to hear an appeal by Mirowski Family Ventures, or MFV, concerning its ongoing litigation against Medtronic (NYSE:MDT) over certain implantable defibrillator patents licensed by MFV to Boston Scientific.

In January, the Supremes ruled unanimously that MFV must prove Medtronic’s devices are in violation, even though Medtronic filed the original patent challenge in 2003, while still under a sub-license agreement for the technology.

MFV had petitioned the high court to revisit a lower court decision that Medtronic did not infringe MFV’s patents, which were sub-licensed to Medtronic through Guidant’s then-owner, Eli Lilly. Boston Scientific (NYSE:BSX) acquired Guidant in 2006.

Last spring, the U.S. Court of Appeals for the Federal Circuit ruled that the high court’s decision meant Judge Susan Robinson of the U.S. District Court for Delaware must reconsider whether Boston Scientific and MFV provided enough proof to withstand Medtronic’s validity challenge.

MFV represents the estate of Dr. Michel Mirowski, who helped invent the implantable defibrillator. The group, which controls several patents related to implantable cardioverter defibrillators and cardiac resynchronization therapy devices, has been pursuing patent infringement cases against both Medtronic (NYSE:MDT) and Boston Scientific (NYSE:BSX) for years.

In late September, a Maryland circuit court ordered that Boston Scientific pay MFV $309 million in back royalties and damages.