376 U.S. 225 (1964)
Stiffel Company secured design and mechanical patents on a pole lamp.1 The lamp was a vertical tube having lamp fixtures along the outside and constructed to stand upright between floor and ceiling.2 Pole lamps achieved commercial success after Stiffel brought them to market.3 Sears, Roebuck & Company subsequently placed on the market a substantially identical lamp that it sold at a lower price.4 Its retail price matched Stiffel's wholesale price.5
Stiffel brought an action against Sears in the United States District Court for the Northern District of Illinois.6 Its first count claimed that Sears had infringed the patents by copying the design.7 The second count alleged that Sears had engaged in unfair competition under Illinois law by causing confusion in the trade as to the source of the lamps.8 Evidence introduced included the absence of identifying tags on Sears lamps, although labels appeared on the cartons delivered to customers.9 Additional evidence showed customer inquiries to Stiffel about differences from Sears lamps and complaints from two customers who had purchased Stiffel lamps upon learning of the cheaper Sears versions.10
After determining that the patents were invalid for want of invention, the District Court found as a fact that Sears' lamp was a substantially exact copy of Stiffel's.11 The lamps were so alike in appearance and functional details that confusion between them was likely and had already occurred in some cases.12 The court then entered judgment against Sears on the unfair competition claim.13 It enjoined Sears from selling or attempting to sell pole lamps identical to or confusingly similar to Stiffel's lamp.14 The court also ordered an accounting to determine profits and damages.15
The Court of Appeals affirmed the District Court's judgment.16 The Supreme Court granted certiorari to consider the question presented by the case.17
Whether a State’s unfair competition law can, consistently with the federal patent laws, impose liability for or prohibit the copying of an article which is protected by neither a federal patent nor a copyright?18
Federal patent laws enacted under the constitutional grant of power establish uniform national standards.19 These standards promote invention through strictly limited monopolies while preserving free competition by dedicating unpatented articles to the public domain.20 State unfair competition laws may not encroach on this scheme by granting equivalent perpetual protection.21
No. The District Court held the patents invalid for want of invention, so the pole lamp stood in the public domain under federal law and Sears possessed the right to copy its design exactly.22 Sears exercised that right by marketing substantially identical lamps at a lower retail price.23 The lower courts nevertheless imposed liability solely because the copied lamps created a likelihood of confusion as to source, without any showing of palming off.24 This application of Illinois law conferred on Stiffel the practical equivalent of a patent monopoly over an unpatentable article.25
It directly undermined the federal policy that limits protection to genuine inventions for a fixed term and then releases the design to unrestricted competition.26
The Supremacy Clause therefore bars the state-law judgment, which must be reversed so that Sears may sell the unpatented lamps without liability for unfair competition.27