A Cure for Written Description and Enablement Headaches: Prior Art

Why It Matters

The ruling lowers the evidentiary burden for biotech patents that rely on functional definitions, enabling broader protection with fewer exemplars and influencing drafting strategies across the pharmaceutical industry.

Key Takeaways

• Single example can satisfy written description if genus was well‑known
• Federal Circuit emphasizes prior art for functionally defined method claims
• Teva’s win shows jury verdict can influence enablement analysis
• One disclosed antibody may represent an entire therapeutic class
• Patent strategy now must document common knowledge of target families

Pulse Analysis

The Federal Circuit’s recent decision in Teva Pharmaceuticals International GmbH v. Eli Lilly clarifies a long‑standing gray area in patent law: when a functionally defined genus can be adequately described by a single example. The case arose from Eli Lilly’s alleged infringement of Teva’s anti‑CGRP antibody patents for migraine treatment. While the district court dismissed the patents for lacking written description and enablement, the appellate court reversed, holding that the specification’s disclosure of one antibody, together with well‑known prior‑art antibodies and human‑generation techniques, satisfied both requirements.

The ruling hinges on the concept that a genus whose members were already part of the public domain at the priority date need not be exhaustively listed. By treating the anti‑CGRP antibody family as a well‑known therapeutic class, the court accepted a single representative example as sufficient to enable the claimed method of treatment. Importantly, the Federal Circuit gave weight to the jury’s finding of infringement, reasoning that a person of ordinary skill would have understood the breadth of the disclosed class from the prior art.

For biotech and pharmaceutical companies, the decision signals a shift toward leveraging prior‑art references to streamline patent drafts. Counsel should now document the common knowledge of target families and provide clear functional definitions, rather than enumerating every possible variant. Litigators can also cite jury verdicts to bolster enablement arguments, though reliance on factual findings remains case‑specific. Ultimately, the judgment offers a pragmatic pathway to protect method‑of‑treatment claims without over‑detailing each molecule, potentially reducing filing costs and accelerating protection for innovative therapies.