Well--that would be unfair. These cases can win for the defendant on defenses unforeseeable to the plaintiff.
Given the number of LLC plaintiffs who have filed expired-mark cases against more than 10, 20, 40, and even (for one plaintiff LLC) 80 defendants, it really seems they don't care too much about winning or losing, nor care about the unforeseen defenses a defendant might have.
All they do is note an expired patent, and then make what is essentially a fraud-type allegation with no more evidence than the bald assertion of "information and belief" that the defendant (i) knew the patent expired; (ii) recognized the fact that this expired patent was still on its product packaging; and (iii) purposefully then kept the expired patent on the product packaging in order to deceive the public. That's all you need for these suits. You could churn them out in your sleep, nearly for free.
So it's not about what unknown defenses the defendant may have. The plaintiffs don't care about them and I suspect know full well that there's none of these expired-mark cases where they're going to get
any proof of intent to deceive (
[1]reasons below).
The business model here is to file against large numbers of defendants, hoping to extract early settlements based on the typical corporate desires to avoid business disruption and legal fees. For the most part, any given case [EDIT:
that is not settled early] will go through summary judgment briefing and hearing, which is going to cost ca. $200,000 to defend. And the discovery burden on the corporation is as large as for any typical litigation (by "burden", I mean disruption to business), while there is essentially zero discovery burden on the plaintiff.
So, going back to the word "unfair", is it possibly unfair (or even a tiny bit unethical) for a law firm to form a plaintiff LLC for purposes of suing dozens of "expired marking" defendants, when said plaintiff LLC knows it won't (and doesn't really plan to) win any given case on the merits, but does hope for some nice settlements? Of course, from the plaintiff LLC standpoint, all they are doing is availing themselves of the advantages given by the law, as interpreted by the courts. No harm no foul, eh?
[1] From a corporate standpoint, patent marking on packaging has one purpose only - to avoid the loss of past damages associated with notice. Other than that single legal criterion, other stakeholders (marketing, regulatory) would prefer to use the space for other things like eye-catching graphics or slogans, or to enlarge the font describing precautions, etc. Consumers simply do not pay any attention to patent numbers on a package, so from a marketing standpoint, they're worthless to a company.
Please note that none of the above commentary (nor any of the acrimony that may have seeped in) applies to other than these "expired markings" cases. There is actually a small minority of these false marking cases where (based on the complaint) it appears one company did indeed try to fend off competition by alleging a false patent protection status (and in one case, sending letters to the competitor's customers), and so the competitor is suing on that ground. Good for them.