Factual Determinations and Patent Law's Intrinsic/Extrinsic Divide: The Common General Knowledge Case Study

To what extent can statements made by an applicant, intrinsic to a patent specification, be accepted as facts? Is this question context-dependent, or is there a hard-line rule that applies across the board? Should it matter what patent law issue is involved: patentable subject matter; obviousness; claim construction? Perhaps most importantly, why does this question matter? What is at stake? This piece argues that there should be a judicial apprehension towards recognizing the blanket proposition that applicant statements within a patent specification can be accepted as matter of fact supporting a determination regarding common general knowledge. Specifically, there should be a judicial apprehension towards endorsing the acceptance of statements made within a patent specification as factual determinations regarding the state of the art or common general knowledge of a hypothetical skilled artisan, when such assertions lack reference to any factual source that is extrinsic to the patent document. Broadly, this piece argues that the law/fact distinction should be drawn along the corresponding intrinsic/extrinsic distinction.