In its recent landmark Bilski non-decision, the Supreme Court held that the now-famous “machine-or-transformation test” (MOTT), although “a useful and important clue,” is not the sole test for determining the patentability of process claims. Fortunately for the legion of lawyers who will now earn vast sums of money litigating the question, the Court did not indicate what other test might apply. Well, to the chagrin of the lawyers, the Court Of Appeals For The Federal Circuit (CAFC) has now stepped in to fill the vacuum.

A patent is invalid if it is shown to be “obvious” in view of a combination of prior art references (35 USC §103). Patentees, of course, will argue that the proposed combination of references is the product of “impermissible hindsight.” In support of such arguments, the patentees will point to “secondary indicia of patentability.”

In patent law, a “product” or “article” claim covers (well, duh) a product. A “process” claim covers a method of doing something – like making a product. A product claim is infringed by the unauthorized making, using, selling, offering for sale or importing the patented product. A method claim is infringed by the unauthorized practice of the patented process. A third, less well-known, type of patent claim is the “product-by-process” claim which covers a product produced by a particular process¹. What infringes a product-by-process claim?