It’s 2024, but patent attorneys and judges still can’t agree whether a preamble is limiting to determine potential patent infringement. One recent district court case tees up this issue in style.

District court Chief Judge Colm F. Connolly was presented the issue of whether the preamble “a vaccine” was limiting or not in Alnylam Pharmaceuticals v. Pfizer et al., Docket No. 1:22-cv-00336 (D.Del. Mar 17, 2022).

There’s a lot to unpack in this relatively binary determination. Federal Circuit precedent tends to find preambles not limiting (meaning, not an element needed to be proven to show patent infringement). Especially so, in language that states purpose or intended use of an invention.

But the Federal Circuit has held that “[t]he preamble limits the claimed invention if it is ‘necessary to give life, meaning, and vitality to the claim.” Marrin v. Griffin, 599 F.3d 1290, 1296 (Fed. Cir. 2010). That’s long for “it depends.”

To his credit, Judge Connolly observed: “I am unable to resolve in an intellectually honest way the conundrum before me.” He ultimately decided to find the phrase “a vaccine” limiting, and observed “that this case well illustrates the need for the Federal Circuit to jettison its rulings that treat language in the preamble of a patent claim as not limiting the scope of the claim.”

Whether you agree with Judge Connolly’s decision or not, the honesty of the decision is refreshing and it is high time for clarity on whether a preamble is to be limiting.