The Supreme Court today overturned Federal Circuit precedent regarding the law of indefiniteness of patent claims. The Federal Circuit had previously held that a patent claim passes muster under 35 U.S.C. §112, (a) [previously ¶2] and is not indefinite so long as the claim is “amenable to construction,” and the claim, as construed, is not “insolubly ambiguous.” The Supreme Court overruled the Federal Circuit and stated that a patent is invalid for indefiniteness if “its claims, read in light of the patent’s specification and prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention.” The Supreme Court therefore remanded the case to the Federal Circuit for further findings in view of the correct standard.

The standard of “reasonable certainty to those skilled in the art” is easier to prove than the “insolubly ambiguous” standard and will increase the likelihood that patent claims can be invalidated for indefiniteness. This new standard will generally help those facing suits for patent infringement.

Interestingly though, the “reasonable certainty” test appears to be a question of fact, i.e., would a person of skill in the art be “reasonably certain” about what the scope of the patent claim was at the time of issuance. By contrast, the Federal Circuit’s now-overruled “insolubly ambiguous” standard was determined as a question of law under claim construction generally. On the whole, while patent infringement defendants may have another tool to try to invalidate patent claims for indefiniteness under the friendlier standard of “reasonable certainty,” that determination will necessarily be a fact issue that is disfavored at summary judgment and would have to be determined at trial.