When may an inventor place the words patent pending on a product? The answer is that the product may be marked patent pending as soon as the patent application is filed. However, care must be taken to remove this marking if the patent application is later abandoned — or the patent is issued but no longer is in force (e.g., expired).
Under 35 U.S.C. 292, whoever falsly marks a product can be fined up to $500 per offense. And the Federal Circuit has ruled that an “offense” means each false marking. Thus, if a company makes a million products marked falsely with an expired patent number, it can (at least theoretically) incur a fine of $500 million. Furthermore, the law allows private individuals to sue the manufacturer. If the plaintiff prevails, the proceeds are split with the government.
In the last year, a cottage industry has been formed to sue manufacturers for false marking. According to one source which closely tracks such lawsuits, the law firm of Mcdonnell Boehnen Hulbert Berghoff, [s]ince January 1, 2010, hundreds of qui tam lawsuits have been filed for false patent marking.” However, not all manufacturers accused of false marking are forking over money. Case in point is Wham-O, the makers of the Frisbee, sued for allegedly including expired patent numbers on their product . Now Wham-O is appealing the constitutionality of the false marketing statute itself. The Federal Circuit heard arguments this week … but most likely, the U.S. Supreme Court will have the final say.