35 U.S.C. (the patent statute) § 102(b)’s bans the patenting of inventions in “public use” in the United States more than one year before the application for the patent was filed.  This is traditionally called the “on-sale” bar and is intended to force inventors to quickly bring new inventions into the patent process, and to assure the public that on-sale and unpatented goods are not subject to the sudden emergence of a later patent.

But there’s more to the “on-sale” bar, as the Federal Circuit recently reminded us. In Barry v. Medtronic (read here), the Federal circuit pointed out that the one-year test has an important corollary, and has previously held that “the public use bar is triggered where, before the critical date, the invention is in public use and ready for patenting.”  Dr. Barry, an orthopedic surgeon, invented a unique tool for correcting spinal curvature cases. He performed three surgeries with his device but testified that only after a year’s follow-up of the last patient’s x-rays and clinical progress, was he able to decide that the device had been a success and should be patented.

The Court acknowledged that more than a year had passed between the surgeries and the patent application, but agreed with Dr. Barry that the invention could not be described as successful without proper clinical follow-up, and that therefore Dr. Barry fell within the “experimental use” exception to the on-sale bar, and that the bar was defeated.

The court pointed out an important qualification, that use can still be experimental until an invention satisfies scrutiny that it is useful for “its intended purpose,” and if there are questions of durability or long-lasting results inherent in an invention’s “intended purpose,” then an experimental stage can last a good long time.

THE BUSINESS TAKE AWAY: The “on sale” bar is a potent obstacle to patenting because it is one of the relatively few absolute deadlines in achieving a patent. At the end of the 365th day of public use, the blade usually drops and the invention is forever barred from a patent. The experimental use exception is an equally potent defense. It must be remembered, as the Court pointed out in Barry, that the real test is suitability for an invention’s “intended purpose,” and that questions of durability or long-lasting effect can extend the experimental period much farther than we might think.