The U.S. Supreme Court case Illinois Tool Works Inc., et al. v. Independent Ink, Inc., 2005 revolved around the issue of patent tying in antitrust law - a practice where a company uses its monopoly over one product to gain an advantage in another market. In this case, Illinois Tool Works (ITW) had patented a system for printing barcodes and required customers to purchase their unpatented ink as part of the deal when buying or leasing their printers. Independent Ink challenged this arrangement under antitrust laws claiming that ITW was unlawfully leveraging its patent power into the ink market. However, the Supreme Court ruled unanimously in favor of ITW stating that possession of a patented item does not automatically confer market power on its owner; hence it cannot be presumed anti-competitive without evidence proving otherwise. This ruling significantly altered how courts approach cases involving alleged patent misuse through tying arrangements by requiring plaintiffs to prove both elements: ownership of a dominant product and coercion forcing consumers into purchasing tied products.

In the dissenting opinion for Illinois Tool Works Inc. v. Independent Ink, Inc., Justice Stevens argued that a patent does not necessarily confer market power upon its holder and thus should not be presumed to do so in antitrust cases involving tying arrangements. He contended that this presumption is inconsistent with modern economic understanding of patents and can lead to unjustified findings of liability under the Sherman Act. Furthermore, he pointed out that Congress has never explicitly endorsed such a presumption in its legislative enactments or amendments related to patent law or antitrust law. Therefore, he believed it was inappropriate for courts to continue applying this outdated legal doctrine without clear statutory support.