When Arbitron rolled out its portable people meter on Monday, two days early, it was a preemptive move against New York Attorney General Andrew Cuomo, who had threatened suit to block it, contending the new radio measurement system undercounts minority listeners.

Cuomo may still file suit, perhaps today, as he'd promised. But the chances that Cuomo, or anyone else, for that matter, will roll back the PPM appear slight to none.

Once up and running, the new electronic system is all but a done deal, in the minds of analysts and industry watchers.

There will surely be court challenges to the PPM that could go on for months, even years, but the likely outcome is that the radio rating service would be forced to adjust the sample panel it uses to collect the data to better reflect the demographic makeup of the population in each market.

If for instance it were found that in the New York market Hispanics were underrepresented, the courts could order Arbitron to add more Hispanics to its New York panel, but it would not direct Arbitron to switch back to the old paper diary system.

Courts are generally reluctant to order companies to do things that would cause major disruptions in the marketplace, as would the rollback of the PPM once it's become the currency in a particular market between radio stations and media buyers. There would have to be a compelling reason.

“The question isn’t whether the product, once introduced, can be withdrawn,” says an executive with a group actively fighting the PPM rollout.

“The courts have done that with automobiles and prescription drugs--where life and health are in danger. For media diversity, while important, a court may find that a bit of a stretch.”

What's far more likely to happen is that the opposition to the PPM in New York and other markets will lead to delays in its rollout in other markets, like Detroit and Atlanta, which have large ethnic populations and where the PPM is set to replace the diary later this year.

“The issue is whether the next group of markets goes to currency,” says the executive.

On Monday, Arbitron replaced its paper diary system with the electronic PPM in eight markets, including Los Angeles, Chicago and New York. The PPM has been in use in Houston and Philadelphia for more than a year, but the diary is still the measurement tool to track local audiences in nearly 300 other markets.

While most media buyers support the PPM, some ethnic stations are seeing steep ratings declines, which has led to Cuomo’s involvement and a back-and-forth between Cuomo and Arbitron.

In rolling out the PPM a couple of days early, Arbitron also filed suit in federal court to prevent Cuomo from blocking the release of PPM data.

But more than the courts, Arbitron has time on its side.

The longer the PPM is used by media buyers and stations, the more comfortable people become with the data, flawed or not, and the less likely any court will move to force a rollback.

“As each day goes by, the agencies are going to get used to using these numbers,” says Tom Taylor, publisher of radio newsletter Taylor on Radio-Info. “The agencies want these numbers, and they’ve always wanted them. So this is it.”

Says David Joyce at Miller Tabak in New York:

“We’re in the early stages of this. It’ll take a while to hash out. But buyers have a better measurement. While they don’t want to see lower listenership to radio, they do want to know with greater certainty what they’re paying for.”