Chapter §12.02 Two Types of Double Patenting

• Jurisdiction: United States

§12.02 Two Types of Double Patenting

Case law recognizes two varieties of double patenting: (1) "same invention-type" double patenting and (2) "obviousness-type" double patenting.¹⁰ Consider again the example of an inventor who has already patented invention X and files a second patent application in the USPTO.

[A] Same Invention-Type Double Patenting

If the later (second) application claims the identical invention X as claimed in the applicant's already-issued patent, the USPTO will enter a rejection for "same invention-type" double patenting. "Identical" in the context of same invention-type double patenting means the two claims being compared are "identical in scope."¹¹

The courts view the "same invention-type" double patenting rejection as based on the language of 35 U.S.C. §101. The statute provides that "[w]hoever invents or discovers any new and useful [invention] may obtain a patent therefor. . . ." (emphasis added).¹² Same invention-type double patenting is thus interchangeably referred to as "statutory" double patenting.

[B] Obviousness-Type Double Patenting

Contrariwise, if the later-filed application does not claim an invention identical in scope to the invention X as claimed in the applicant's patent, but rather claims a patentably indistinct or merely obvious variant of invention X, the USPTO will enter a rejection for "obviousness-type" double patenting. This form of double patenting is recognized in judicial decisions based on policy concerns with improper extension of the term of patent protection, but does not have an explicit basis in the patent statute.¹³ Hence obviousness-type double patenting is interchangeably referred to as "nonstatutory" double patenting.

The obviousness-type double patenting analysis generally involves two steps. Consider the hypothetical of two issued patents owned by the same entity and a litigation in which an accused infringer asserts that the second patent is invalid for obviousness-type double patenting over the first patent. To carry out the double patenting analysis, a court will first interpret the claims of the first patent and the claims of the second patent and determine the differences between the properly interpreted claims. Then the court will proceed to determine "whether the differences in subject matter between the . . . claims render the claims patentably distinct."¹⁴ If the differences in subject matter between the claims do not render the claims patentably distinct, then the second patent is...