Parker-Hannifin Corp. v. Wix Filtration Corp. 2006 WL 3028706 (E.D. Cal.) Judge Levi In denying a preliminary injunction, Judge Levi stated ââ?¬Å?[p]otential lost revenue alone does not qualify as ââ?¬Ë?irreparable harmââ?¬â?¢ because, otherwise, there would be ââ?¬Ë?irreparable harmââ?¬â?¢ in every patent case.ââ?¬Â? To be awarded a preliminary injunction, a patent owner plaintiff must show:

(1) a reasonable likelihood that it would succeed on the merits; (2) a threat of irreparable harm; (3) the balance of hardships tips in its favor; and (4) the public interest favors granting the injunction.

Parker designs and sells oil filtration systems and replacement filters for the Ford F-150. Wix also sells replacement filter elements, which compete with the products sold by Parker. Parker claims Wix infringes its patent covering the filter design (the ââ?¬Ë?426 patent), and additionally that the Wix products are defective and cause failed fuel injectors in the F-150 which Parker fears Ford may blame on the Parker oil filtration system. There is no actual evidence that any of the Wix products are faulty, and Wix claims that these warranty claims predate the sale of its products by several years. The only physical difference in the filters is that the Wix filter includes an additional plastic tube inside the filter apparatus, so the question is whether this tube acts to distinguish the Wix filter from the Parker filter. After concluding Parker has not proven likelihood of success on the merits, Judge Levi discusses irreparable harm:

Mere loss in revenue from competition is not “irreparable harm” in a patent infringement suit when the plaintiff has failed to demonstrate that it will likely succeed on the merits.

Does this imply if likelihood of success on the merits is shown, loss of revenue would be sufficient? A strong arguement can be made that lost revenue is not irreparable because that is exactly what the award of damages is intended compensate. Preliminary injunctions, especially after eBay, should be much more difficult to obtain. Plaintiff�s loss of revenue, alone, should rarely be sufficient to allow a preliminary injunction.