Federal Circuit Emphasizes Importance of Prosecution History in Resolving Ambiguous Terms of Claims in University of Massachusetts v. L’Oreal USA, Inc. | Haug Partners LLP

[co-author: Ann Bolton]

On June 13, 2022, the Federal Circuit issued a notice of precedent that overturned the district court’s judgment of indefiniteness, ruling that the decision was based on an erroneous interpretation of the claim.1 The patents in suit claimed methods of improving the skin by topical application of compositions containing adenosine.2 The independent claims contain two clauses which state a concentration range of adenosine.3 The first clause refers to “the topical application to the skin of a composition comprising adenosine”.4 The second clause states a range of “concentration of adenosine applied to dermal cells”, which are cells below the surface of the skin (the surface of the skin is the epidermis).5 This made the language of the claim ambiguous as to whether the claimed concentration range is the concentration of adenosine in the composition itself, or is rather the concentration that is permeated into the subterranean dermal cells.6 The District Court determined that the plain and plain meaning of the language of the claim is that the stated range is the concentration of adenosine in the dermal cells, rather than the concentration in the composition.seven Noting the distinction between the two clauses, which both referred to concentration, the district court held that the claims were indefinite because they were ambiguous and entered a final judgment of invalidity.8

On appeal, the Federal Circuit Panel determined that the wording of the claim was ambiguous, but explained that the district court should have looked at the specifications and prosecution history to try to resolve the ambiguity before taking a decision. decision on indefiniteness.9 Despite the claim’s ambiguous wording, the Federal Circuit determined that the specification and suit demonstrated that the claim would be understood to refer to the concentration of adenosine in the composition.ten Thus, the Federal Circuit reversed the district court’s indefiniteness ruling and returned the case to the district court to proceed under the new claim interpretation.11


The University of Massachusetts and its exclusive licensee, Carmel Laboratories, LLC, (collectively, “UMass”), filed an infringement action in 2017 in the District of Delaware against L’Oréal SA and its U.S. subsidiary, L’Oréal USA , Inc. (“L’Oreal”).12 The action related to patents claiming a method of improving skin without increasing skin cell growth by applying a topical composition containing a specified concentration of adenosine.13 The patent specifications describe human skin as having two primary layers: the epidermis, which is the surface layer, and the dermis, which is the deeper layer containing dermal cells.14 The independent claims contain two clauses which have made the claims ambiguous.15 The “skin enhancement clause” states “the topical application to the skin of a composition comprising a concentration of adenosine”.16 The claims then end with a “wherein clause” which states “wherein the concentration of adenosine applied to the dermal cells is 10-4 M to 10-seven Mr.”17 The issue on appeal was whether the indicated range referred to the concentration of the product applied to the skin, as argued by L’Oréal, or to the concentration infiltrated into the dermal cells after application, as argued by supported UMass.18

What is relevant to the decision is that in March 2018, L’Oréal filed motions for inter partes examination of the two patents, which the Patent Trial and Appeal Board (“PTAB”) rejected.19 In denying the petition, the PTAB adopted the UMass construct that the clause in which states the concentration of adenosine in subterranean dermal cells.20

The district court accepted the PTAB’s interpretation, determining that the where clause “has its plain and plain meaning without the need for further interpretation.”21 Insisting on the distinction between the concentration mentioned in the where clause and the skin improvement clause, the district court granted L’Oréal’s petition for indefinite invalidity.22

Federal circuit analysis

On appeal, the construction of the claim was revised de novo.23 The Committee explained that the words of a claim are generally given their plain and plain meaning, but this must be considered in the context of the specification and prosecution history, particularly when resolving ambiguities.24

The Panel began its analysis with the wording of the claim and concluded that, in the context of the claim as a whole, the wording was not clear on its face.25 The Panel first noted that the word “apply” refers to the skin in one clause and the dermis in the other, but decided that “this does not mean that different things are applied”.26 On the contrary, the same concentration “can be applied directly to one object and indirectly to another”.27 Next, the Panel explained that the where clause contains the phrase “the adenosine concentration”, suggesting an antecedent link to the previous clause’s reference to “adenosine concentration”.28 Finally, the committee felt that under the construction of UMass requiring the concentration to be measured in dermal cells, then the claim would refer to a concentration that did not exist before the composition was applied. If so, the Panel concluded that such an interpretation would therefore require that the clause in which be rewritten to clarify that the concentration is measured after application and suffusion.29

The committee then reviewed the specification and noted that none of the embodiments described as “the invention” specify a concentration measurement “after infiltration through the skin into the dermis – much less a concentration measurement as the amount of adenosine per unit volume of dermal cells.30 UMass argued that the specification deals with experiments that directly exposed dermal cells to the cited concentrations of adenosine in a laboratory setting, but that did not convince the committee that the invention would include “the measurement of concentrations under the surface of the skin after topical application”.31

Finally, the Committee determined that the prosecution history provided the strongest evidence to resolve the ambiguity regarding which clause.32 A predecessor to the independent claim, which was later modified by the wording of the patent claims, did not contain a where clause but did contain a separate dependent claim which included the concentration range but made no mention of skin cells.33 To overcome a rejection of the prior art, the applicants added the clause in which in the independent claim and at that time added the wording “applied to dermal cells”.34 Notably, in response to the Bureau’s action, the plaintiffs described the changed wording to the Examiner and suggested that the addition of “skin cells” to the clause did not change where the concentration should be measured.35

The committee ultimately decided that although the wording of the claim appeared ambiguous at first glance, the specification and, more importantly, the prosecution history demonstrated that the claim referred to the concentration of adenosine in the composition.36 As the Panel explained, “[b]Because the meaning of the language of the relevant claim is unclear, but rather ambiguous”, the court “may turn to the prosecution history to “illuminate the meaning of the disputed claim phrase and resolve an ambiguity otherwise left unresolved”.37 Thus, the Panel[held] that this litigation history requires that the reference to the clause in which the cited concentrations are “applied to dermal cells” be read as referring to the concentrations of the composition applied to the surface of the skin. »38

The impact and conclusions of the decision

The Panel’s decision and reasoning demonstrate that ambiguous wording of a claim should be resolved, to the extent possible, on the basis of the intrinsic record before concluding that a claim is indefinite.39 In this case, the Panel looked beyond the plain and ordinary meaning of the claim’s terms and assessed the description and litigation history to resolve the ambiguity.40 Thus, it is apparent from the Panel’s view that terms of claims that are otherwise ambiguous can be interpreted in a manner that resolves the ambiguity based on the intrinsic record.

1 Univ. of Mass. vs. L’Oreal SA, n° 2021-1969, sheet op. at 1 (Fed. Cir. Jun. 13, 2022).
2 ID.
3 ID. at 3.
4 ID. at 8.
5 ID.
6 ID. at 5.
seven ID.
8 ID. at 6.
9 ID. at 8.
ten ID. at 14.
11 ID. at 7 O’clock.
12 ID. to 2. The tribunal de grande instance upheld L’Oréal SA’s motion for inadmissibility for lack of personal competence. That decision was overturned on appeal, and the Federal Circuit ruled that UMass had the right to make jurisdictional discovery. ID. at 3.
13 ID. at 3.
14 ID.
15 ID. at 8.
16 ID.
17 ID.
18 ID. at 6.
19 ID. at 4 o’clock.
20 ID.
21 ID. at 5.
22 ID. at 6.
23 ID. at 7 O’clock.
24 ID.
25 ID. at 8.
26 ID. at 8-9.
27 ID. at 9 o’clock.
28 ID.
29 ID. at 10.
30 ID. At 11 o’clock.
31 ID. at 12.
32 ID.
33 ID. at 13.
34 ID.
35 ID.
36 ID. at 8.
37 ID. at 14 (citing Custom Media Commc’ns, LLC c. Apple Inc.952 F.3d 1336, 1345 (Fed. Cir. 2020)).
38 ID.
39 ID. at 7 O’clock.
40 ID.