AUXILIUM PHARMACEUTICALS, INC v. UPSHER-SMITH LABORATORIES, INC.

The doctrine of equivalents protects patentees from copyists using unforeseeable equivalents that perform the same function in substantially the same way to obtain substantially the same result as a patent claim.

Opinion (Robinson): Auxilium Pharmaceuticals, Inc. ("Auxilium") filed an infringement action against Upsher-Smith Laboratories, Inc. ("Upsher-Smith") in the U.S. District Court of Delaware. Auxilium alleges Upsher-Smith infringed upon its ‘968 patent claims covering a treatment for hypogonadism using a specific chemical formulation of testosterone gel. The parties had stipulated previously that Upsher-Smith’s formulation did not literally infringe Auxilium’s patent, and so the only remaining issue was if Upsher-Smith violated the doctrine of equivalents. While the application of the doctrine of equivalents in this case seems counter-intuitive because it protects patentees from copyists using unforeseeable equivalents, its function is to incentivize patentees to claim all foreseeable variations. In other words, only inventions using unforeseeable alternative means to perform the same function in substantially the same way to obtain substantially the same result as a patent claim in question will infringe against that patent. The ‘968 claims focused on cyclic Hsieh enhancers, whereas Upsher-Smith’s formulation used Dudley enhancers. The Court found the Dudley enhancers were known in the art at the time because Auxilium specifically discussed the Dudley enhancers in their claim and differentiated the Hsieh enhancers as not obvious in light of Dudley enhancers. Because the Court found the use of Dudley enhancers was foreseeable there was no violation of the doctrine of equivalents. Upsher-Smith’s motion for summary judgment was GRANTED.