Cybor Corp. FAS Technologies, Inc. 138 F.3d 1448 (1998) FAS invented and got a patent on a pump for squirting liquids onto semiconductors. They sued Cybor, who had a patent on a similar pump, for infringement. Cybor argued that the claims of their patent were different than the claims in FAS's patent. At trial, the Judge looked at the words in the claims, and told the Jury what those words should be interpreted to mean. Basically, the Judge was the one who construed the meaning of the claims, not the Jury. The Trial Court found for FAS and invalidated Cybor's patent. Cybor appealed. Cybor argued that the Trial Court misconstrued the claims in their patent. Cybor argued that how claims should be construed was a question of fact for a jury to decide, and not a question of law for a judge to decide. The Appellate Court affirmed. The Appellate Court found that there are two steps to an infringement analysis: First, the judge determines the scope and meaning of the patent claims asserted. Second, the properly construed claims are compared to the allegedly infringing device. The Court looked to Marksman v. Westview Instruments, Inc. (517 U.S. 370 (1996)), and found that claim construction was a question of law for a judge to decide. It is arguable that that is what the US Supreme Court actually said in Marksman. More likely, the US Supreme Court found that claim construction was a mixed question of law and fact, but that for various reasons it was more practical to let a judge decide than a jury. The Court looked to how the Trial Judge construed the claim construction, and agreed with his analysis. In a dissent it was argued that the US Supreme Court in Marksman didn't say that claim construction was a pure matter of law, they said that it "falls somewhere between a pristine legal standard and a single historical fact." The problem with assuming that claim construction is purely a question of law has to do with appellate review. Appellate courts review questions of law de novo and do not have to give any deference to what a trial court decided. If there is a question of fact, than the trial court is given some deference because they were there to actually see the witnesses and evidence. That means that pretty much every loser at the trial level will appeal because they get a free 'do-over' at the appellate court, and that's inefficient. In a concurrence, it was argued that since claim construction is a mixed question of law and fact, the appellate courts should grant deference to the trial courts in their judgment.