Troll is a bit confusing as a term here - these 'marking trolls' are manufacturing companies stamping fraudulent or misrepresented patents numbers or patent pending claims on a product.
Whoever marks upon, or affixes to, or uses in advertising in connection with any unpatented article, the word “patent” or any word or number importing that the same is patented for the purpose of deceiving the public … Shall be fined not more than $500 for every such offense. 35 U.S.C. § 292.
The statute also prohibits falsely marking products with the words “patent pending” or “patent applied for” with the purpose of deceiving the public. The statute has a broad standing provision that permits “any person” to sue for the penalty and split the proceeds with the federal government.
They don't need to have any connection with the offending firms, and they get half the fine as a bounty. At $500 per item, that's quite a haul! In the original case, a lawyer noticed his coffee cup was stamped with out-dated patent numbers, so imagine the potential fine there.
Why exactly do we need to pay a lawyer $250 per coffee cup to stop this? Leaving patent numbers on designs you've been selling for decades is a technical violation, but this sort of bounty-seeking loophole is a terrible way to stop it.
Better info here: http://www.foley.com/publications/pub_detail.aspx?pubid=6695
Whoever marks upon, or affixes to, or uses in advertising in connection with any unpatented article, the word “patent” or any word or number importing that the same is patented for the purpose of deceiving the public … Shall be fined not more than $500 for every such offense. 35 U.S.C. § 292.
The statute also prohibits falsely marking products with the words “patent pending” or “patent applied for” with the purpose of deceiving the public. The statute has a broad standing provision that permits “any person” to sue for the penalty and split the proceeds with the federal government.