Patentees use claim differentiation to broaden the scope of patents.Independent claims must be different from and broader than their dependents, according to the doctrine, resulting in an inevitable expansion of the independent claims. §112(d) seldom gets its due, and when it does, courts wrestle with the apparent chicken and egg problem of whether to apply the statute or claim differentiation first. Section 112(d) must be applied first, or it would be rendered a nullity.Congress considered several mechanisms for aligning revenues more closely with operational costs, including incentivizing use of dependent claims which Congress recognized “may be analyzed more expeditiously in the Office,” and thus examined more cheaply.
In this way, claim differentiation creates an incentive for patentees to include dependent claims in their patents, even if such dependent claims appear to add little or nothing to the independent claims.
Given the “primary importance” of claims in interpreting patents, it should be no surprise that judges frequently rely upon claim differentiation to tip the scales in favor of giving patents a broader scope.
Rather, that section merely required that the claims, whatever their form, particularly point out and distinctly claim the applicant's invention.
Some practitioners questioned the validity of dependent claims in absence of a statutory provision clearly sanctioning them.
He had never seen the PTO perform a substantive analysis of validity under Section 112 paragraph (d). This shows that a similar analysis could be done for dependent claims. Not undertaking such an analysis may well be rational.