In the filing, the Direct Marketing Association (DMA), American Association of Advertising Agencies and Association of National Advertisers, among others, point to comScore’s “standard-setting role in internet commerce”, with its data “used to establish online advertising rates”.

The parties state that: “In this particular case, an improper certification order has the probable impact of not only harming defendant comScore by chilling voluntary participation in its market research, but also adversely impacting many of the amici’s members who rely on web rating services of the defendant and companies like it.”

In addition, the brief says that the parties are “alarmed by the ease with which plaintiffs were allowed to suspend disbelief and obtain certification of a class challenging disclosures that plainly advise panelists that comScore’s system will comprehensively monitor all activity and configurations on the computer to which it is downloaded”.

Web users Mike Harris and Jeff Dunstan first sued comScore in 2011. They allege that the company exceeded the scope of a consumer’s consent to monitoring by intercepting phone numbers, social security numbers, usernames, passwords and credit card numbers, among other personal information.

ComScore has said that the claims in the lawsuit are “without merit”. However in April, Federal Judge James Holderman certified a class of “all individuals who have had, at any time since 2005, downloaded and installed comScore’s tracking software onto their computers via one of comScore’s third party bundling partners”. Holderman also certified an additional subclass of “all class members not presented with a functional hyperlink to an end-user licence agreement before installing comScore’s software onto their computers”. Estimates put the size of the class at up to a million people.