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In a battle that has stretched across courtrooms and years, Johnson & Johnson’s DePuy Synthes told a Delaware federal judge Monday that a jury got it wrong when it ordered the company to pay $12 million to RSB Spine for infringing spinal fusion patents under the doctrine of equivalents.

Both companies landed back in court with dueling post-trial motions, each side trying to tilt the scales of justice one final time. DePuy insists it never violated the patents; RSB Spine argues the opposite—and says it’s owed even more money for sales made after the jury reached its verdict.

A Verdict Interrupted

The dispute stems from a December 2022 win for RSB Spine. But before judgment could be entered, U.S. District Judge Richard G. Andrews held a separate bench trial to evaluate DePuy’s argument that it, not RSB, developed the surgical technology first. The judge rejected that claim in August, clearing the path for this latest round of legal fire.

Though jurors ruled DePuy did not commit direct infringement, they concluded the company stepped over the line under the doctrine of equivalents. Monday’s filings focused on only one of the two patents involved.

DePuy: Patent Amendments Block Equivalents

DePuy’s core attack leans heavily on prosecution history estoppel—a doctrine that stops patent owners from reclaiming territory they narrowed during the application process. According to DePuy, RSB Spine amended its patent to avoid conflicts with earlier inventions by restricting the orientation of a screw hole.

“By amending claim 1 to overcome prior art, RSB surrendered claim scope,” DePuy argues, saying its own devices fall squarely within that surrendered ground. The company adds that RSB gave up additional equivalence rights through positions it previously took before the Patent Trial and Appeal Board.

A Challenge to the Heart of the Patent

DePuy also contends the jury’s equivalence finding effectively erased key patent limitations. In one vivid example, the company drew a hard line between bone with a lip osteophyte and bone without one—arguing the two are clinical opposites and cannot be treated as equivalents without destroying the patent’s meaning altogether.

RSB Spine Seeks More Damages

RSB Spine, for its part, is pushing to finalize supplemental damages. Its expert based earlier calculations on estimated sales figures at the time of trial, with the understanding they would be revised when real sales data became available. DePuy has already agreed to provide that information, and both sides appear aligned on how to calculate pre- and post-judgment interest.

RSB is also pursuing damages for post-trial sales, applying the same 6% royalty rate the jury decided on. The company argues it is legally entitled to compensation until the patent expires.

“Plaintiff is entitled to post-verdict damages … to ensure it is fully compensated,” its brief states.