As the reader may (should) remember, an article claim of a patent is infringed if all of the claim limitations are found in the accused product. Note that this statement is silent as to when the claim limitations must be present. A recent case turns on that fascinating – to patent attorneys – issue. Gemtron Corporation v. Saint-Gobain Corporation

As the reader may (should) remember, basically there are two kinds of patent claims: article claims¹ and method or process claims. Article claims are comprised of multiple article limitations, and method claims are comprised of multiple steps or process limitations. Both types of limitations are fine but, just as we are abjured to mix milk and meat, so too we are directed – albeit by a different authority – not to mix article limitations and process steps in a single patent claim. Rembrandt Data Technologies, LP v. AOL LLC et al.