The Process Patent Amendment Act (PPPA - Title 9 of the Omnibus Trade and Competitiveness Act 1988 codified at 35 USC § 271 (g)) provides for process patent protection by amending the U.S. Patent law to provide that the owner of a U.S. patent relating to a process of production of goods can exclude others from using, selling offering for sale or importing products made by that process into the United States. [188] Protection does not, however, exist if the product in question is one that is being materially changed by a subsequent process or if the product becomes a trivial and non-essential component of another product. The exact meaning of this provision is not entirely clear and the legislative history of the statute seems to imply that Congress intended the provision to apply to processes claiming intermediates in a multi stage process for preparing a final product even though only the final product was imported into the United States, but only if production of that intermediate was an effective bottleneck controlling the whole process. [189]

A product will only be caught by the act if the process by which it was made was carried out after the patent issued so that importation of a product into the United States will not be an infringement under this provision even if it occurs after the grant of the patent in question if the actual manufacture abroad took place before the grant of the U.S. patent. [190] Furthermore, no remedy shall be granted for infringement on account of a non-commercial use or retail sale of an imported product that is the result of a patented process unless there is no other adequate remedy for infringement on account of the importation or other use or sale of the product.

Remedies available under the provisions are further limited in respect of those who were merely using an infringing product without knowledge that it was the product of a patented process. Certain tests are set out for determining whether one was "innocent" so as to result in a possible limitation on the remedies given to the patentee for such use or sale. The most significant feature of these is a presumption of good faith on the part of the alleged infringer if he has inquired of one engaged in the manufacture of the product whether there are any patents that person "reasonably believes could be asserted to be infringed" if the product was imported, sold or used in the United States. In making such a request, the requester must agree to draw his supplier's attention to any patents that are listed by the manufacturer to whom the request was made and request an assurance that no process covered by a listed patent is used in the production of the product in question. Unless there are mitigating circumstances, failure to make such a request will be regarded as showing a lack of good faith. Any patent owner who has marked all of his goods sold in the United States with the number of a process patent that will be infringed by their production is, however, relieved from the obligation of replying to any such inquiry. [191]

The Process Patent Amendment Act also provides that the burden of proof of asserting infringement of a process patent may be reversed in cases where the action is based on the importation, sale, offer for sale or use of the product of a process patented in the United States, if the court finds that "a substantial likelihood exists that the product was made by the patented process and the plaintiff has made a reasonable effort to determine the process actually used in production of the product by the defendant and was unable to so to determine." [192]

An attempt to broaden the interpretation of the legislation to include not only process claims, but also claims to materials used in a process carried out abroad failed in the case of Amgen Inc. v U.S. International Trade Commission. [193]