Antecedent Basis: A Lesson for Claims Drafters from a Professional Claims Reader

Antecedent basis is a judicially created requirement that stems from Section 112(b)


by: Mitch Kline | August 1, 2017

Through working with the great number of patents that come across my desk, (at least) one thing has become clear: too many of them have an antecedent basis problem. Of the plethora issues that might cause the downfall of an otherwise valuable patent, antecedent basis troubles are, at once, among the easiest to avoid and the most difficult to mitigate (depending on the severity).

Antecedent basis is a judicially created requirement that stems from Section 112(b), which mandates that claims “particularly point [] out and distinctly claims [] the subject matter which the inventor or a joint inventor regards as the invention.” This is referred to as definiteness—a claim is indefinite when it contains words or phrases whose meaning is unclear. In re Packard, 751 F.3d 1307, 1314 (Fed. Cir. 2014).

Thus, the requirement that each claim element must have an antecedent basis. Essentially, this boils down to using an indefinite article (e.g., a or an) before a noun or noun phrase the first time that noun or noun phrase is introduced. When that noun is used subsequently throughout the claim, it should be preceded by a definite article (e.g., the or said). That’s it. That’s the whole thing. There are cases that turned entirely on the use of the word the, when the drafter should have used the word a.

Again, the rule is rooted in the need for definiteness, so a misstep does not necessarily doom a patent. Section 2173.05(e) of the MPEP explains using an example from Ex Parte Porter, in which “controlled stream of fluid” provided reasonable antecedent basis for “the controlled fluid.” A misstep will, however, cause a significant headache for the patent owner (at the least), and so should be avoided, if at all possible.

Luckily, I have devised a system—simple, usable, and elegant—that can help. It consists of five steps:

  • Draft a claim;
  • search for the words “the” and “said”;
  • take note of each noun (or phrase) preceded by the words “the” and “said”;
  • search for each of the nouns noted in 3); and
  • if there is not an instance of each noun, noted in 3), that is also preceded by the word “a” or “an,” FIX IT.

Bonus: now make sure that each noun or phrase identified in 2) is the one to which you meant to refer.

So there you have it. No charge. This one’s on me.


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