In recent years the Patent Office has reversed its previous view that product by process claims are permissible only if the product in question cannot be defined in any other way. The exact scope of such claims is a matter of controversy. Patent Office practice, however, is to permit such claims only if the product itself rather than its method of production is novel [160] and the applicants bear the burden of proof to show such novelty. [161]

In 1991 a substantial controversy arose over a Federal Circuit Court of Appeals decision which held that a product by process claim (that is to say a claim along the lines "product X whenever obtained by carrying out process Y") could be infringed by sale or use of product X even though this had been produced by a totally different process. [162] The court reasoned that since in determining questions of patentability in order to secure grant of a product by process claim one had to show that the product itself was novel, there was no reason why a similar standard should not apply to questions of infringement.

The issue came before a different panel of the Federal Circuit a year later in the case Atlantic Thermoplastic Company Inc. v. the Faytex Corp [163]. This time the court undertook a detailed analysis of the history of product by process claims going back to an 1877 Supreme Court decision. By tracing the history of Supreme Court and Court of Appeals decisions throughout the United States the court this time came to the conclusion that in order to infringe a product by process claim it was necessary that the process used for production of the product was that specified in the claim. In a footnote the court noted that its previous decision had been based on a "undeveloped record" and had not considered the prior case law on the subject.

In the later decision the court recognized that, in determination of patentability, it was appropriate to construe product by process claims broadly and to ignore the process limitation. This was justified because permitting inventions to be defined in product by process form was an exception from the general principle, laid down in many cases, that an article should be defined by its structure rather than its manner of manufacture and, therefore, the only reason why product by process claims were permitted at all was to reduce the burden on the applicant in defining his invention. Providing this facility, however, did not water down the basic requirement that the product itself must be novel in order to establish patentability. In assessing infringement, on the other hand, case law had traditionally held that the scope of a product by process claim was limited by the process stated and referred to a Supreme Court decision of 1884 (Cochrane v. Badische Anilin & Soda Fabrik [164]) as precedent for this conclusion. The Federal Circuit panel hearing the Atlantic Thermoplastic case believed that this was still good law today.

The issue has not yet been reconsidered at the Federal Circuit level. However, some district courts have felt that since Scripps was the first of the two panel decisions by the Federal Circuit and there has been no en banc decision by the circuit court overruling it, Scripps is the decision to be followed. [165]