In patent law lingo, an "interference" pits two patents covering the same invention against each other. The prize consists in getting the earlier "priority" date so that Patent A trumps Patent B.
In Henkel Corp. v. Procter & Gamble Co., No 06-1542 (Fed. Cir. May 11, 2007), the court reviewed a decision by the U.S. Patent & Trademark Office Board of Patent Appeals and Interferences to award Procter & Gamble’s patent priority over Henkel’s. The invention concerned dishwashing detergent tablets that feature two regions with different dissolving speeds. The Board held that the Henkel inventor’s earlier creation of such a wondrous tablet didn’t count because he didn’t have the folks in the lab measure the relative dissolving times. The Federal Circuit disagreed, holding that "appreciating" what the Henkel inventor invented didn’t require precise determination of how fast each part of the tablet melted, only that one melted at a "greater" rate than the other.