There's been some back and forth on this issue. To plead a claim for false marking, a plaintiff must allege that the defendant marked something as patented with an "intent to deceive the public." Does a plaintiff asserting a false making claim need to satisfy the heightened pleading requirements of Rule 9? The Federal Circuit provided an answer yesterday:
This court holds that Rule 9(b)'s particularity requirement applies to false marking claims and that a complaint alleging false marking is insufficient when it only asserts conclusory allegations that a defendant is a "sophisticated company" and "knew or should have known" that the patent expired.
a complaint must in the 292 context provide some objective indication to reasonably infer that the defendant was aware that the patent expired.