In August, comScore sued three startups, claiming their products for measuring ad viewability violated comScore’s patents. I explained here why I thought the claims were pretty lame at the time.

One of those startups is fighting back. Moat acquired a patent of its own and countersued comScore.

The company denies allegations that it infringed on comScore’s patents. What’s more, Moat has accused comScore of suing in bad faith and committing fraud.

The suit is about whether one company (comScore) has the right to be the only player in the market that measures whether or not a digital ad has actually been seen. ComScore’s own patents were acquired after the company was sued over the same issue by Nielsen. As I wrote in August: I see it as a revenge lawsuit. ComScore got dragged into a messy patent battle and emerged unprofitable with a bunch of vague patents, which it has decided to use for evil, in my opinion.

So naturally Moat dug around the comScore-Nielsen lawsuit and found some gems. Defending itself against Nielsen, comScore itself argued that these patents are invalid. From Moat’s suit: “comScore stated that [e]ach and every claim of the ’680 patent is invalid for failing to meet the requirements for patentability including, without limitation, one or more of Sections 101, 102, 103, 112, and 116 of Title 35 of the United States Code.”

ComScore then became the proud owner of the supposedly invalid patents, which it is using to put three relatively established startups out of business (the other two are AdSafe and DoubleVerify).

Moat has also accused comScore of fraud. ComScore promoted a “viewable impression” standardized form of measurement widely in the industry without disclosing, until now, that it holds a patent on viewable impressions. That’s kind of a problem — the entire industry is spending money and energy supporting the IAB’s Making Measurement Make Sense initiative and trying to make its products fit into that viewable impression standard. According to Moat, they’ve been doing it not knowing that one big player in the industry will sue them once they do. From the suit:

comScore had a duty to disclose any of its patents it asserts relate to or cover the proposed standard to IAB members, including Moat (an Associate IAB Member). On information and belief, comScore never disclosed any of its patents and their alleged applicability to the proposed standard. In so doing, comScore intentionally mislead Moat and the other IAB members by failing to disclose its patents.

Part of the problem here is that adtech is often bought and sold on a sales pitch. Results are so easy to manipulate and product descriptions are so drenched in jargon that it’s often difficult to tell what’s real and what’s snake oil. But the industry is hungry for solutions, which is why adtech startups have been able to scale quickly. Moat has a relatively novel approach to viewability that uses mouse-overs as a proxy for clicks to measure user attention.

Now the company has a patent of its own. Moat went to the secondary patent market — that such a thing exists is news to me — and bought itself one from a company called C3i which no longer sells ad products. The patent is about as broad as the 15-year-old patents comScore is suing Moat with, which should make this difficult for a judge and interesting for us observers.