North Carolina Journal of Law & Technology


Michael Xun Liu


Subject matter eligibility and functional claiming are considered separate doctrines in patent law. Conceptually, subject matter eligibility relates to the types of ideas that can be patented, whereas limits on functional claiming constrain how patentees can claim their inventions. In practice, however, patents that recite functional claims are also more likely to be invalidated for failing to recite patentable subject matter. This trend is especially prevalent in the software field, where courts often hold the function or end result of a computer program represents an unpatentable abstract idea.

Critics argue this judicial approach to software patents improperly conflates “what is patentable” with “how patentees can claim their inventions.” To rein in this practice, Congress has introduced legislation that would narrow judicial authority over patentable subject matter. The current legislative proposals, however, do not address underlying policy issues surrounding functional claims in software patents. They will also prevent courts from invalidating patents that broadly preempt future innovation. Instead of limiting judicial authority over patentable subject matter, policymakers should address functional software claims more directly, such as adopting a more flexible interpretation of means-plus-function claims under 35 U.S.C. § 112(f) or delegating rulemaking authority to the Patent and Trademark Office (“PTO”).

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