How can a claim be indefinite even if it appears clear on its face?
A claim can be indefinite even if it appears clear on its face when there’s a conflict or inconsistency between the claimed subject matter and the specification disclosure. This inconsistency can render the scope of the claim uncertain. The MPEP 2173.03 states:
“A claim, although clear on its face, may also be indefinite when a conflict or inconsistency between the claimed subject matter and the specification disclosure renders the scope of the claim uncertain as inconsistency with the specification disclosure or prior art teachings may make an otherwise definite claim take on an unreasonable degree of uncertainty.”
This principle is supported by case law, including:
- In re Moore, 439 F.2d 1232, 1235-36, 169 USPQ 236, 239 (CCPA 1971)
- In re Cohn, 438 F.2d 989, 169 USPQ 95 (CCPA 1971)
- In re Hammack, 427 F.2d 1378, 166 USPQ 204 (CCPA 1970)
For example, in In re Anderson, a claim was found indefinite because the terms used in the claim were vague when compared to the structures described in the specification.
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