In August, news network New Delhi Television (NDTV) took the somewhat unprecedented legal action of suing Television Audience Measurement Media Research India — a joint venture of the Nielsen Co. and Kantar Media — by claiming $810 million in advertising revenue was lost over eight years because of alleged manipulation and corruption of viewership data.

“People have always questioned Nielsen,” says Erwin Ephron, a veteran media research advertising exec who worked for Nielsen and now runs the New York-based Ephron Consultancy. “But no one gets to the point of suing them.”

These days, Ephron says there is much more oversight when it comes to TV viewer data in the U.S. and around the world.

For example, in the U.S., he says, “There are around 100 research companies all competing with each other. They have a very good idea of what the data responds to.”

The U.S. also has an ombudsman, the Media Ratings Council.

NDTV has subscribed to TAM Media India since 1998. The ratings agency has been a key part in helping the territory achieve its $2.3 billion TV advertising market.

India has a population of 1.2 billion, with an estimated 129 million homes with TV services.

TAM Media India says it is among the top five data measuring services in the world, with the largest sample size comprising 36,000 individuals across 162 cities and towns, covered by 8,150 people meters, according to its website.

But NDTV says these figures are too low and that TAM Media India continues to publish ratings despite repeated recommendations to raise the sample size.

Typically, securing a bigger viewership sample means getting more money from TV networks.

“It’s up to Nielsen and the market stakeholders to determine what level of service can be provided for what reasonable price,” says Todd Juenger, media analyst for investment research firm Bernstein Research. “I’m sure Nielsen would be happy to add to the sample if it was paid more.”

Nielsen execs wouldn’t comment about the case, but WPP Group — the advertising agency holding company that owns Kantar — filed legal papers to dismiss the suit for a number of reasons, including that the filing was done in the wrong jurisdiction (New York) and that NDTV’s lawsuit erroneously names business units of Kantar and Nielsen and personnel that aren’t involved in the TAM Media India service.

WPP says NDTV’s legal efforts are driven by declining ratings.

“The case is nothing more than a desperate attempt by the defendant, a television station in New Delhi, to drum up media coverage and divert attention from the real reasons its programs have had low ratings and its financial performance has been abysmal for the last five years,” says WPP in its legal filing.

“It has gotten publicity and it’s on my radar,” says Brad Adgate, senior VP of New York-based media agency Horizon Media. “But I don’t think it’ll have any effect in the U.S.,” he adds.

Ephron says, “Marketers can be more impressed with the data than the effect. Nielsen numbers are intermediaries. The data alone doesn’t mean anything. The question is, how much does the advertising deliver?”

A rare lawsuit recently filed by an India-based TV group against a local TV rating service for alleged viewer data malpractice doesn’t look like it’s going to change the way media buyers and sellers operate, say analysts.