Patent Wars: The University of Minnesota and AGA Medical’s Clash Over Septal OccludersPatent Wars: The University of Minnesota and AGA Medical’s Clash Over Septal Occluders

Since medical device related patent applications often describe multiple inventions, the parent applications often are divided into several subsequent patents, each describing a particular invention. When the inventions described in a parent patent application are divided into multiple subsequent patent applications, the use of previous disclaimers of scope to overcome subsequent prior art anticipation allegations will not be effective unless there is a substantial similarity among the patents’ claim limitations.

Among other issues reviewed, in Regents of the University of Minnesota v. AGA Medical Corporation, the US Court of Appeals for the Federal Circuit held on June 3, 2013 that “a prosecution disclaimer will only apply to a subsequent patent if that patent contains the same claim limitation as its predecessor.” With this in mind, this recent decision affects how applicants and attorneys can cross-pollinate disclaimers among the various patent family applications.

The University of Minnesota owned US patent 6,077,281 (the ‘281 patent) directed to septal occluders for blocking holes in the septum and repairing the heart. As a defense to allegations of infringing the ‘281 patent, AGA Medica

AGA Medical argued that the ‘281 patent was unenforceable because it was invalid as being anticipated by prior art patents. The ‘281 patent used a means-plus-function style claim with the function of “moving the member from a compressed orientation to an expanded orientation.” For purposes of such a means-plus-function claim, “an equivalent of the described structure merely performs the same function as the disclosed structure, in substantially the same way, with substantially the same result.”

AGA Medical alleged that a prior art patent had a springy “radial” frame that indeed performed the same function, insubstantially the same way, with substantially the same result as that described in the U of M patent.
In response, the University argued that during examination of its prior patent in the same family, it specifically disclaimed the use of a radial frame as an equivalent of the peripheral frame. This disclaimer was effective to overcome a prior art rejection in this prior patent. However, the relevant claim in this prior patent did not include a means-plus-function element as does the ‘281 patent. Moreover, the basis for distinguishing the prior art in the prior patent was not the same as how this new prior art is being applied to the ‘281 patent. And, the scope of the ‘281 patent is not the same as the claim in the prior patent.

For these reasons, the court decided that because the language in the later ‘281 patent claim was significantly different from the prior patent, the disclaimer did not apply. Accordingly, in order for disclaimers to carry over to subsequent patents, it is “necessary to support the inference that the patentee’s earlier arguments are also applicable to the claim limitations of the patent-in-suit.”

Clark A.D. Wilson is a Partner at the Atlanta, Georgia based Intellectual Property law firm Gardner Groff Greenwald & Villanueva PC. Prior to joining Gardner Groff, Clark was a corporate Patent Attorney for a medical device unit of Novartis. Clark holds a Master of Engineering (M.Eng.) in Bioengineering from the University of Maryland and is Board Certified in Intellectual Property law by the Florida Bar Association.