This is part one of a three-part series on written description requirements and the developing case law under the America Invents Act (AIA).

It happens regularly in patent litigation: a patentee asserts a patent that arose from a child application, the child application claims priority to an application filed years before, and the development of prior art in the intervening years affects the outcome of the litigation. In various cases, the outcomes (along with millions of dollars in damages) have hinged on the teachings of a parent application.

One such case involved the alleged infringement of a medical device patent for artificial hip implants. Tronzo v. Biomet, Inc., 156 F.3d 1154 (Fed. Cir. 1998). The patentee filed a “parent” application in 1984, and its claims were so specific in their geometry that the patentee could not prove any infringement of those claims. Rather, the infringement theory was based upon claims in a later patent application filed in 1987, having broader claims that were not limited by the particular shape of the cup.

Even though the patentee won the trial, he lost on appeal. One reason involved his own British application which was published in 1985 – more than a year before the child application. This publication would bar patentability unless his patent claims from the 1987 application could rely upon the 1984 effective filing date. Crucially, the appeals court determined the 1984 (parent) application did not contain adequate written description of a generic shaped acetabular cup, but was limited to “conical” and “trapezoid” for the shape. The court held that there was not substantial evidence to support the jury’s finding of adequate written description in the 1984 application for the later-filed claims in the 1987 application. Accordingly, the generic claims of the later-filed application were not entitled to the earlier filing date, and the patent was invalidated.

This particular case involved a parent application, a later-filed child application, and the development of some additional prior art during the intervening years. Here, it was the inventor’s patent application published in 1985. Now, the America Invents Act (AIA) presents another type of development for patent attorneys to consider. Specifically, any child application filed after March 16, 2013 is deemed a “transitional application,” if it claims the effective filing date of a parent application on or before March 16, 2013. By definition, all transitional applications that straddle the March 16th date lay claim to an earlier-filed application. If that claim to an earlier-filed application is not justifiable, however, the AIA’s more rigid first-to-file scheme applies.

We have yet to see a wave of cases presenting these issues, but we will. It has only been about 19 months since the AIA transition date. District court cases involving patent claims from a transitional application, if any, will still be in the very early stages of litigation and certainly will not have reached appellate review stages yet. However, these issues will undoubtedly arise. Which law applies – the AIA or pre-AIA law? Is the later-filed application entitled to the effective filing date of the pre-AIA parent application? Is additional prior art from the intervening years available to challenge the patent? All who practice in our field will want to stay abreast of questions like these.

Courts in some cases will use the written description test to determine such issues. For a claim in a later-filed application to be entitled to the filing date of an earlier application, the disclosure of the earlier application must comply with the requirements of 35 U.S.C. § 112, paragraph 1, which includes an adequate written description. For the earlier disclosure to meet this requirement, it must reasonably convey to one of skill in the art that the inventor possessed the later-claimed subject matter at the time the parent application was filed.

Future posts in this series will examine other written description cases, and consider how pre-AIA written description cases will guide courts in determining whether the AIA applies. Such cases will generally fall into one of two categories: (1) those where the disclosure in the parent application was too narrow to support the broader claimed subject matter of the later-filed application; and (2) genus-species cases. The law under the AIA is still developing. But what is certain is that courts and litigators will have to address not only new art that is disclosed during intervening years between a parent and child application, but also the choice-of-law issues that depend on whether § 112, paragraph 1 is satisfied.