Under U.S. law, every patent claim must be supported by an adequate written description, which conveys to those skilled in the art the nature and breadth of the invention. The Federal Circuit recently decided two cases that found that claiming both a quantitative value and a quantitative range requires particular clarity in the disclosure.
In Indivior v. Dr. Reddy’s Laboratories, Indivior appealed an inter partes invalidation of claims reciting polymer percent weight ranges in orally dissolvable films. Indivior argued that disclosure of specific formulations with the lower quantity of a claimed range (48.2 wt %) and the upper quantity of a claimed range (58.6 wt %) was sufficient to encompass the claimed ranges (40 wt % – 60 wt % and 58.6 wt % – 60 wt %). The Court disagreed and found that disclosing examples having only the upper and lower limits of a range is not sufficient to claim an entire range, stating that “more clarity is required” for adequate written description support of the claimed range. The Court further rejected Indivior’s argument that if one looks to the specification’s tables and creates a range from the polymer weight percentages in the examples, then one has obtained the range. The Court stated that this act would “amount to cobbling together numbers after the fact” and that Indivior did not demonstrate that a person of skill in the art would have understood that the specification was disclosing a range of polymer weights. Thus, the Federal Circuit affirmed the PTAB’s holding that the claims were invalid as lacking adequate written description.
In Biogen Int’l GmbH v. Mylan Pharms. Inc., Biogen appealed the district court’s holding that the specification lacked an adequate written description for the claimed method of treating multiple sclerosis (MS) with 480 mg/day of dimethyl fumarate (DMF). The Court noted that while the specification may arguably support method-of-treatment claims that use DMF to treat MS, a person of skill in the art would have to look in the specification for dosing information. The Court found that the specification provided little guidance on dosing. The specification’s single incidence of the claimed 480 mg/day dose is listed as the lower endpoint of the range “about 480 mg/day to about 720 mg/day,” which is further listed in a series of dosage ranges not linked to treatment of a specific disease, including 200-800 and 240-720 milligrams per day. As a result, the Court found that the district court did not err in finding that a person of skill in the art would not have recognized, based on the single passing disclosure of the 480 mg/day dose, that 480 mg/day would have been efficacious in the treatment of MS.
The test for adequate written description “is whether the disclosure of the application relied upon reasonably conveys to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date.” In these cases, patentees attempted to claim a range from individual values (Indivior) and attempted to claim an individual value from a disclosed range (Biogen). In both instances, the Federal Circuit found the disclosures insufficient to support the claims. These decisions make clear that the description of individual values within a range will not necessarily convey that the inventor had possession of the entire range. Further, the inclusion of an individual value bounding a disclosed range will not necessarily be sufficient to convey that the inventor had possession of the individual value in the absence of additional guidance. In practice, applicants should consider whether a specification provides clear support for a range or for a particular value when making claim amendments in order to avoid written description issues in future proceedings.
 35 U.S.C. § 112(a).
 Indivior UK Ltd. v. Dr. Reddy’s Labs. S.A., No. 2020-2073, 2021 WL 5500526 (Fed. Cir. Nov. 24, 2021).
 Id. at *10.
 Id. at *10.
 Biogen Int’l GmbH v. Mylan Pharms. Inc., No. 2020-1933, 2021 WL 5571708 (Fed. Cir. Nov. 30, 2021).
 U.S. Patent No. 8,399,514 at 18:61-62.
 Id. at 18:60-61.
 Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en banc).