Background
Mr. Hantman adopts the title of a talk by the Honorable Howard T. Markey, then the Chief Judge of the Court of Appeals for the Federal Circuit, at the University of Chicago Law School on April 26, 1983. Judge Markey is quoted, "[W]hen it comes to patent cases, the statute is the law -- and court opinions containing language and concepts contrary to the statute are unlawful."

Judge Markey's remarks, according to Mr. Hantman, should have been directed to the Court of Appeals for the Federal Circuit (CAFC, the appeals court for all patent litigation in the U.S.) since it is not applying the law as it existed when the Federal Circuit was created in 1982. Instead, in the nineteen years of its existence, the CAFC has developed a body of law on the major issues of patent procurement and patent enforcement using language and concepts contrary to the statute that are difficult to understand and even more difficult to implement.

The doctrine of equivalents
According to Hantman, the key statutory provision that the CAFC has not followed is Section 112, para.6, enacted by Congress as part of its 1952 patent statute revisions. Under Hantman’s theory, Congress enacted this provision specifically to overrule certain Supreme Court cases, including the Court’s 1950 decision in Graver Tank v. Linde Air Products. In Graver Tank, the Supreme Court held that a defendant’s invention could infringe a plaintiff’s patent not only by infringing the patent’s claims literally but also by infringing under the so-called "doctrine of equivalents" -- that is, by performing the same function in the same way to achieve the same result as the plaintiff’s invention.

Thus the Graver Tank opinion used the doctrine of equivalents to expand the scope of a patentee’s claims. Hantman argues that the doctrine of equivalents had previously been used only to restrict the scope of a patentee’s claims and that Congress, through the 1952 patent legislation, intended to return the law to its pre-Graver Tank state. Hantman also claims that prior to the creation of the Federal Circuit, its predecessor courts tended to follow the intent of the 1952 revisions. By contrast, according to Hantman, the Federal Circuit has used the doctrine of equivalents in an expansive fashion clearly rejected by Congress. This, he argues, is not only contrary to the statute but it also creates too much uncertainty regarding the scope of the patent.

Hantman also suggests that certain other Federal Circuit doctrines, such as its interpretation of product-by-process claims and its pre-2000 interpretation of a complex patent law doctrine known as prosecution history estoppel (which limits the expansive scope of the doctrine of equivalents) are contrary to the patent statute. With respect to these doctrines, however, the statutory provisions to which Hantman is pointing are not specified.

Limitations
Hantman’s interpretation of how the doctrine of equivalents by the courts was used prior to Graver Tank is subject to dispute. More importantly, it is by no means clear that Congress intended the 1952 patent amendments to rein in use of the doctrine of equivalents as a mechanism for expanding patent scope. Indeed, Hantman’s view of Congressional intent was rejected by the Supreme Court in the 1997 Warner-Jenkinson v. Hilton Davis case.