This post was first published on July 17, 2014.
A transitional phrase is a part of the claim that connects the preamble and the body. The Transitional phrase determines as to whether a claim is “Open” “Partially Open” or “Closed.”
An Open claim includes additional unrecited elements i.e., if a claim, which is Open, recites elements A, B, C and D, then an article which includes elements A, B, C, D and E infringes the Open claim irrespective of the fact that the article has an extra element E which is not recited in the Open claim.
The term “comprising” in a claim makes the claim Open.
In, Gillette Co. v. Energizer Holdings, Inc., 405 F.3d 1367 (Fed. Cir 2005), a famous and much talked about case, the claim at issue recited “A safety razor blade unit comprising a guard, a cap, and a group of first, second and third blades. ” The accused infringing product included four blades. The court said that the word “comprising” makes the claim Open and hence, the scope of the claim encompasses all safety razors satisfying the elements set forth in the claim thus concluding that the accused product infringed the claim.