Don’t Be Barred: Reminder to Inventors and Patent Applicants – Do NOT Bring Your Invention into Public View Before Filing a Patent Application




The Federal Circuit’s recent decision in Minerva Surgical, Inc. v. Hologic, Inc. provides a timeline reminder to inventors and patent applicants: Do not bring your invention into public view before you have filed your patent application, and if you do, remember the one-year critical date for filing. Otherwise, your patent runs the risk of later invalidation.

A Little Background about Minerva Surgical

The invention in Minerva Surgical is a medical device for stopping or reducing abnormal uterine bleeding. In relevant part, the device has a frame with flexible outer elements in contact with a surface that is applied against the uterine lining, and flexible inner elements not in contact with the surface, “wherein the inner and outer elements have substantially dissimilar properties.” Such a frame allowed the device to maintain a small size for insertion but could expand to conform to the uterine wall to stop bleeding.

Minerva first began developing this device in 2008. By August 2009, Minerva lab notebooks demonstrated that a device having a frame with inner and outer elements having substantially dissimilar properties had been identified as a solution to the problem of being able to insert, apply, and remove the device during surgeries without deformation. Inventor testimony further confirmed that the key elements of the frame’s characteristics were known to Minerva’s research and development team by August 2009.

Unveiling the Device

In November 2009, Minerva brought the device to a major gynecological surgery conference held by the American Association of Gynecologic Laproscopists (AAGL). Fifteen fully functional devices were brought to the conference, which was well attended by doctors who would be potential customers. The Minerva booth gave demonstrations of how the device operated, and the chairman of Minerva’s medical advisory board gave a presentation featuring the device. The booth and the general literature highlighted the flexible frame. After the conference Minerva continued to develop the medical device and ultimately arrived at its full, final design.

The earliest patent application was filed on November 7, 2011 — nearly two years after the AAGL conference. A later filed patent application in the family was issued as U.S. Patent No. 9,186,208 (the ‘208 patent).  After Minerva sued Hologic for infringing the ‘208 patent, Hologic won on summary judgment for invalidity of the patent due to anticipation by the alleged 2009 public use of the device. Minerva then appealed.

On appeal, the Federal Circuit reviewed the law concerning public uses or sales under Section 102(b) of the pre-America Invents Act (AIA) patent law. A patent is deemed invalid where the invention was “in public use or on sale” more than one year before the date of applying for the invention in the United States. (While this case involved a patent issued under the laws in place before the AIA went into effect, the Federal Circuit has confirmed in other cases that the standard for finding a “public use or sale,” as the earlier statute was phrased, carried over without change to the AIA’s statutory language defining prior to include an invention “being in public use, on sale, or otherwise available to the public.”) The Federal Circuit applies a two-prong test for finding that the public use bar has been triggered. First, the invention must be “in public use” more than a year before the date of filing. Second, the invention must be “ready for patenting.”

Proving the “Public Use” Bar

To satisfy the first prong of public use, the party challenging the patent must show that the invention “was accessible to the public or was commercially exploited” by the inventor or applicant. Under this set of facts, the Federal Circuit found that the AAGL display and disclosures made the invention “accessible to the public.” The devices brought to the display were “fully functional” in a manner consistent with what was ultimately disclosed and claimed in the ‘208 patent. Minerva demonstrated the device at its booth using a transparent uterine model that made its operation visible to anybody watching and further provided a technical presentation on the device. Minerva tried to argue that a “mere display” of the device did not qualify as public use, but the Federal Circuit found that a “display” only applied to non-working mock-ups, not full demonstrations. The (disputed) fact that Minerva did not allow attendees to actually handle or operate the device did not matter, since in this case Minerva had made the device’s operation clearly visible to anyone walking past the booth. Finally, there were no confidentiality obligations imposed upon any of the doctors, potential investors, or others who visited the booth. The Federal Circuit held that there was no dispute that the device was “accessible to the public.”

Proving the Device “Ready for Patenting”

Turning to the second prong, the Federal Circuit also found no dispute that the device was “ready for patenting.” An invention is “ready for patenting” if it is reduced to practice or is otherwise sufficiently described in documentation to enable a person of ordinary skill to practice the invention. Although only one of these two tests needs to be satisfied, the court found that Minerva actually met both standards. Minerva claimed first that it had not reduced the invention to practice because it had continued to develop the device after 2009 and had not tested the device on live humans (a requirement for FDA approval.) The Federal Circuit dismissed both contentions. Continued developments were not dispositive, the court held, because “later refinements” and “fine tuning” of a claim element do not mean the device is not yet ready for patenting Here, the claim specifically covered the structures that Minerva’s inventors knew to be key to operation as early as August 2009. As to the lack of live human testing, the appellate court simply stated that the level of testing and knowledge for FDA approval is “beyond that required” for showing reduction of the invention to practice. The court also held that the inventor lab notebooks included sufficiently detailed information to allow another person of ordinary skill to follow them and reduce the invention to practice. Having found the invention both “in public use” and “ready for patenting,” the Federal Circuit affirmed the district court’s grant of summary judgment of invalidity.


While Minerva is a straightforward application of the public use bar to invalidate a patent, there are some key takeaways for inventors. First, the critical date is defined by the scope of the claim. If Minerva had a narrower claim, perhaps a dependent claim, that targeted only the later developments, such a narrower claim may have survived because it would not have been subject to the 2009 disclosure. Alternatively, if additional elements were later modified and developed (such as the compliant surface pressed against the uterine wall), including those elements in the claim may have also pushed the claim beyond what was disclosed in 2009. Of course, both of these options mean a narrower claim scope, which perhaps Hologic may not have infringed. But the biggest takeaway is a reminder to all inventors and applicants: Don’t start showing off your device until you have either filed a patent application or decided not to. And if you have displayed the device, make sure to file a patent application within one year from that display to avoid any potential application of the public use bar.