In 01 Communique, the Federal Circuit provided clear guidelines regarding the frequently raised “practicing the prior art” argument.  Quite simply, the argument that a defendant is not liable because the claimed elements existed in the prior art is an invalidity argument, not a non-infringement argument.

By way of background, 01 Communique sued Citrix alleging patent infringement relating to private communication portals.  Citrix argued that its accused products did not literally infringe the asserted claims and the asserted claims were invalid.  In a somewhat Solomon-esque decision, the jury determined that 1) Citrix did not prove that the claims were invalid, and 2) that 01 Communique failed to prove that Citrix infringed the asserted claims.

01 Communique moved for a new trial alleging that Citrix improperly resorted to a “well-known defendant’s trick” by arguing that Citrix’s products were the same as prior art products and therefore, Citrix’s products could not infringe the asserted claims.  The District Court denied O1 Communique’s motion stating that 1) the jury had properly been instructed that infringement analysis requires comparing the asserted claims to the accused product, and 2) that Citrix did not raise a “practicing the prior art” argument in its non-infringement defense.  01 Communique appealed.

In affirming the District Court, the Federal Circuit reiterated that “there is no ‘practicing the prior art’ defense to literal infringement.”  Instead, “literal infringement is determined by construing the claims and comparing them to the accused device, not by comparing the accused device to the prior art.”  Therefore, an accused infringer “cannot defeat a claim of literal infringement or establish invalidity merely by pointing to similarities between an accused product and the prior art.”  Thus, the prior art’s similarities to the accused product does not matter for infringement purposes.

It’s a different analysis when it comes to invalidity.  A frequent defense argument is that, assuming the asserted claims are valid, if the plaintiff tried to expand the scope of its claims to read on defendant’s products, then those claims are invalid in light of the prior art.  The Federal Circuit affirmed that there is “nothing improper about this argument.”  Therefore, a defendant may properly argue “that if a claim term must be broadly interpreted to read on an accused device, then this same broad construction will read on the prior art.”  Thus, in this context, the comparison of the prior art to the defendant’s accused products is relevant, but only by way of limiting the scope of the asserted claim.

That said, a “practicing the prior art” argument is still subjected to the “clear and convincing” standard for proving invalidity, not the “less stringent preponderance of the evidence standard.”  But don’t let the standard scare you — as the Federal Circuit has recognized, if the accused product actually practices the prior art and nothing more, invalidity should be easy to prove.  In fact, “when an accused product and the prior art are closely aligned, it takes exceptional linguistic dexterity to simultaneously establish infringement and evade invalidity.”

In a way, the relevance of the prior art to the asserted claims and accused products seems like procedural semantics. But, as with everything, context matters.