Case 11: Arrhythmia Research Technology, Inc. v. Corazonix Corp. (1992)

Arrhythmia Research filed a plea to have a ruling that a patent belonging to Michael Simson was invalid. The case was heard in the CAFC. Simson's invention charted the electrical signals of the human heart to certain functions by use of electrocardiographs. Heart attack victims are vulnerable to an arrhythmia know as ventricular tachycardia, which may be detected by the use of an EKG. Simson, a cardiologist, patented a way by which a person's vulnerability to such an arrhythmia could be determined.

The patent secures a three-step process. First, certain cardiograph impulses are tracked through sensors and digitized; these impulses are looking for a certain region of activity known as the QRS complex. A large number of these complexes are digitized and averaged. The first part of the QRS segment is isolated and processed backwards in a high pass filter. This is the critical feature of the patent; this step apparently makes the signs of ventricular tachycardia more clear by ridding the signal of other noise. The RMS is then calculated to determine the magnitude of the signals; if the magnitude is under a certain threshold, then the patient is considered at high risk.

The issue of patentability arose from the fact that a computer model calculated several of the values used in the patent, utilizing a number of natural laws and algorithms. The District Court held that this patent was invalid due to a lack of statutory subject matter. While the Supreme Court had previously ruled "anything under the sun made by man" to be patentable, they qualified that statement by ruling that "laws of nature, physical phenomena, and abstract ideas” are not patentable. Mathematical formulae fall under this second category; in its Gottschalk ruling, the Court held that mathematical formulae used in a computer solely for a mathematical algorithm is not statutory material. However, in Diamond v. Diehr, the Court ruled that while mathematical formulae are not patentable, any new and useful structure made with their knowledge is. The Appeals Court found that the Simson material was analogous to the Diehr material in that the Simson patent did not seek the exclusive rights to the formula itself, but rather the formula in conjunction with all the other steps which helped identify high-risk patients. The Appellate Court sent the case back to the District Court so that matter of infringement could be determined.