

MILWAUKEE, WI- SEPTEMBER 22 President Barack Obama delivers a speech to thousands at a grassroots event at the Summerfest Grounds at Henry Maier Festival Park in Milwaukee, Wisconsin on September 22, 2012.

Money in politics just got a little less opaque.

Today's the day a little-known rule by the Federal Communications Commission takes effect for every TV station in the country. In a nutshell, it requires broadcasters that run political ads to disclose who paid for them.

It may sound like a simple idea. But it could have tremendous effects on the way campaigns compete and spend money — not to mention for third-party groups and members of the general public who are interested in campaign finance, too.

Until about two years ago, TV stations — along with cable companies, satellite TV operators and other video providers — had to keep a paper record of who was paying for political advertisements. Anyone could open up those files and look at them; all you had to do was walk in and ask. But that was also the source of a major problem: Unless you physically visited each and every station's office building, there was no way for you to get access to the files.

Starting in 2012, that began to change. Taking advantage of the transition from analog to digital TV signals, the FCC required broadcasters (but not cable or other providers) to begin filing those records online. The rule applied only to the top four stations in the top 50 U.S. markets — a total of 200 stations in all. As of Tuesday, however, the rule about online record-keeping now applies to all broadcasters everywhere that run political ads. That's likely to increase the number of covered stations from 200 to perhaps around 1,000, estimates Dennis Wharton, a spokesperson for the National Association of Broadcasters. There are around 1,800 TV stations in America, but those that don't run political ads, such as public broadcasting stations, won't be affected by the rule.

The disclosure forms are searchable by TV station on the FCC's Web site. They clearly state which candidate an ad supports; the name of the treasurer or other official who's taking out the ad; and the amount of money being paid to broadcasters for the airtime. As an example, this is what a representative for Maryland gubernatorial candidate Doug Gansler filed last month for an ad airing on WUSA in Washington, D.C.:

Here's why the new disclosure method matters more than you might think. Suppose you're running a political campaign. Beginning now, you're going to be able to sit at your computer and find out where your competition has been taking out ads, when they got them for and for how much money. That kind of information may have always been accessible if you were willing to travel to get it, but now you — or any citizen, for that matter — can find this stuff out from your computer.

(To be clear,this does not appear to be the same rule that caused Ted Cruz to hold up the Senate's approval of Tom Wheeler, the FCC's chairman, last year. Cruz was objecting to implementation of the DISCLOSE Act, another effort at campaign transparency.)

Some are already preparing to take advantage of the new data. The Sunlight Foundation, which tracks political spending, has unveiled a new tool designed to search the FCC's TV station database. An early analysis by Sunlight finds that although Americans for Prosperity has not reported spending a dime on campaign ads this year to the Federal Election Commission. But according to the broadcaster data reviewed by Sunlight, "the group has been extremely active in swing states, especially North Carolina and Michigan."

The one drawback? The rule applies only to broadcasters — which limits how much you can learn when political ads are taking on a growing role in the pay-TV space. Cable and satellite TV companies aren't covered under the FCC's rule.

"We think there's a fundamental unfairness in that exception," said Wharton.

The FCC hasn't said anything about whether the rule could be extended beyond broadcasters. But for advocates of greater transparency in politics, this is a start.