Prosecution Disclaimer - Historical Basis and Case Law

Historical Basis and Case Law

Prosecution disclaimer is a common law doctrine that originates in federal court precedent. One discussion and example of prosecution disclaimer is made in the Federal Circuit case Southwall Techs. Inc. v. Cardinal IG Co. This case also cites several other Federal Circuit cases dealing with prosecution disclaimer.

In Southwall, the Court was explicit in defining the principle: "The prosecution history limits the interpretation of claim terms so as to exclude any interpretation that was disclaimed during prosecution". The Court used the principal to prevent the patentee from arguing an interpretation of "sputter deposited dielectric" that would allow it to continue with a patent infringement suit, because the argument was inconsistent with its position during prosecution.

The Court also noted that a given claim term must be interpreted consistently across all claims. Once a term has been given a specific meaning with regard to one claim, the same meaning applies to all claims that include that term.

Another Federal Circuit case using the term "disclaimer" is Standard Oil Co. v. American Cyanamid Co. In Standard Oil, the Court stated that "the prosecution history (or file wrapper) limits the interpretation of claims so as to exclude any interpretation that may have been disclaimed or disavowed during prosecution in order to obtain claim allowance."