A patent claim can be held void under §112 paragraph 2 of the patent act if it is so vague that it does not properly point what the scope of the holder’s patent right under that claim in fact is. Until May 2014 a Federal Circuit standard that “a claim is indefinite if its legal scope is not clear enough that a person of ordinary skill in the art could determine whether a particular product or method infringes or not” prevailed, rendering the indefiniteness defence very difficult to assert successfully. However, in Nautilus, Inc. v. Biosig Instruments, Inc the United States Supreme Court set a new standard – i.e., a patent’s claim is invalid for indefiniteness if, viewed in light of the specification and prosecution history, the claim fails to inform, with reasonable certainty, those skilled in the art about the scope of the invention.
The new standard for indefiniteness is expected to have a very significant impact on the value of many patents and potentially on the activities of so-called patent trolls who have exploited the ambiguity of patent claims especially in software patents to file many lawsuits. When combined with the April 2014 decision of the Supreme Court, Octane Fitness v. ICON, with respect to attorney fee awards under §285 of the patent statute, the use of vague claims to seek nuisance value settlement may now be especially hazardous, especially if the patent holder has advanced wildly differing claim constructions on different occasions.