Panduit Corp. v. Stahlin Bros. Fibre Works, Inc.

A patentee seeking lost profits on sales diverted to an infringer must prove four elements: demand for the patented product, absence of acceptable noninfringing substitutes, manufacturing and marketing capacity to meet the demand, and the amount of profit the patentee would have made. Panduit undisputedly showed demand and capacity, and the court concluded that the master had erred in treating other infringing ducts as acceptable noninfringing substitutes. But failure on any required element defeats a lost-profits award.

Panduit’s proof failed on the profit calculation. Its accounting omitted evidence concerning fixed costs, and Stahlin offered expert testimony contesting Panduit’s theory that those costs could be disregarded. Unlike the prior Sciaky case, in which the infringer had not contradicted the patentee’s treatment of overhead, the record here supported the master’s conclusion that Panduit had not supplied a reliable basis for calculating its incremental profits.

Because the district court adopted the master’s factual findings, those findings could be overturned only if clearly erroneous. The appellate court found no sufficient record basis to label clearly erroneous the finding that Panduit’s omission of cost evidence made a fair lost-profit calculation impossible. The court therefore affirmed the denial of lost profits on diverted sales.

Damages claimed from a forced price reduction rest on the same compensatory principle as damages claimed from lost sales: the patentee must prove the economic loss caused by infringement. Panduit contended that Stahlin’s approximately 30 percent price cut forced it to lower its own prices and thereby lose more than $4 million in profits.

The master credited Stahlin’s accounting and economic evidence over Panduit’s evidence and found that Panduit’s increased sales volume after its price reduction more than offset the lower profit per unit. Thus, according to the master, the price reduction resulted in a net gain in Panduit’s profits.

The court deferred to that credibility-based factual finding because the district court had adopted it and Panduit had not shown clear error. It therefore affirmed the refusal to award price-reduction damages.

Section 284 requires damages adequate to compensate for infringement and guarantees at least a reasonable royalty when actual damages cannot be proved. A reasonable royalty is assessed through a hypothetical negotiation at the time infringement began—here, March 6, 1962—not through hindsight based on later events. The task is not to recreate an ordinary voluntary license negotiation while pretending that the infringement never occurred.

Panduit had a policy of retaining exclusive control of the Walch patent rather than licensing competitors. A royalty set after adjudicated infringement must account for the value of the property right the infringer took, including the patentee’s lost opportunity to retain the market and to earn future profits. Treating the remedy as merely the routine royalty that a willing licensee might have paid would let an infringer impose a compulsory license on an unwilling patentee and create an impermissible “heads-I-win, tails-you-lose” incentive to infringe.

The master’s conclusion that acceptable noninfringing substitutes existed was clearly erroneous. The competing ducts in the market when infringement began were themselves infringing products, not lawful substitutes. The patented duct had recognized advantages over earlier hole-based ducts, Stahlin’s own materials praised those advantages, and Stahlin continued to sell infringing products even after Panduit sued and after the initial injunction. Stahlin’s later ability, when compelled by the injunction, to shift customers to a different product did not establish that an acceptable substitute existed at the critical date in 1962.

Because the substitute finding failed, the related conclusions also failed: Panduit could not necessarily have been forced to abandon its price differential because of substitute competition, and the parties could not be assumed in March 1962 to have anticipated Stahlin’s later 1963 price cut. The record did not support those predictions about the hypothetical negotiation.

The master also improperly relied on an expert’s generalized experience that negotiated patent royalties commonly fell between one and five percent. The expert lacked experience in determining post-infringement royalties under section 284, assumed acceptable noninfringing substitutes existed, and failed to account for the specific commercial realities of this patent. A reasonable royalty must be grounded in the facts of the particular case, including the patentee’s expected profits from exclusivity.

Finally, the master wrongly used Stahlin’s actual overall profit margin as the ceiling-like basis for a royalty that would leave Stahlin a profit. The relevant inquiry was what royalty the parties would have agreed to in March 1962, including the customary profit allowed to licensees in the electrical-duct industry at that time. Whether Stahlin later proved able to earn a profit after paying that royalty was irrelevant; a genuine licensee could have renegotiated or ended an unfavorable agreement, whereas an adjudicated infringer could not invoke its own later economics to reduce compensation.

On remand, the court directed consideration of Panduit’s actual March 1962 profit margin, customary licensee profits in the relevant industry, the lack of acceptable substitutes, Panduit’s consistent no-license policy, the future profits it would lose by licensing a direct competitor, and the fact that the patented invention supplied the duct’s entire marketable value.