Bottom Line: Describing an invention as “may be” having a particular feature is an effective strategy for maintaining the breadth of a claim. By being noncommittal, courts are less likely to interpret specific features as mandatory requirements in the claims. Patent claims can be narrowed based on statements made in the specification and prosecution history. In Cadence Pharmaceutical v. Exela Pharmsci Inc. (Fed. Cir. 2015), the Federal Circuit considered the “buffering agent” limitation in the claims. While the patent’s specification included statements about specific concentration ranges for the buffering agent (e.g., 0.1–10 mg/ml), the court did not limit the claim to those ranges because the specification used the noncommittal phrase “may be.”
The Role of Claims in Defining Patent Scope
Patent protection is defined by the claims, and during litigation, each limitation (or word) in the claim is given meaning. Normally, terms are given their ordinary meaning unless the inventor redefines them in the specification or prosecution history. To do so, the inventor must express a clear intent to act as their own lexicographer.
Insights from the Cadence Case
During trial court proceedings, the term “buffering agent” was construed broadly to mean “an agent that helps the formulation resist change in pH.” The defendant proposed a narrower interpretation, requiring the buffering agent to have a sufficient concentration to prevent a material change in pH. This would have limited the claim, excluding agents that resist pH changes at any concentration but do not materially prevent such changes.
The Federal Circuit rejected the defendant’s argument, ruling that while all embodiments in the specification referenced specific concentrations, importing those levels into the claims would improperly narrow their scope. The court emphasized that the phrase “may be” demonstrated no intent to limit the term “buffering agent” to particular concentrations.
Drafting Tips for Patent Specifications
When drafting a patent specification:
- Use Broad Descriptions: Describe the invention in general terms to cover a wide range of variations.
- Include Specific Details: Add specific examples and details to support arguments for patentability during prosecution.
- Be Noncommittal: Use phrases like “may be” instead of “is” to reduce the risk of limiting claims unnecessarily. For example, state that a buffer’s concentration “may be between 0.1 and 10 mg/ml” rather than definitively asserting it falls within that range.
The Cadence case illustrates how specifics in the specification can potentially narrow claims, but noncommittal language mitigates this risk.
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