The media love to talk about transparency and accountability when it comes to politicians and the government -- they should, it's an important subject. They, too, have such an obligation of transparency to the American people, particularly when it comes to who can and cannot advertise on their coveted airwaves. On that account, they continue to fail miserably.

In 2004, the United Church of Christ produced a television commercial promoting its inclusive approach to organized faith. The ad showed two nightclub-style bouncers guarding the rope line of a church as they denied entry to a gay male couple, several people of color, and a man in a wheelchair. By contrast, a white family of four had no problems getting through.

“Jesus didn't turn people away” was the ad's tagline, but CBS did, turning down the commercial which was intended for broadcast during that year's Super Bowl. The 30-second spot apparently violated the network's policy of “prohibiting advocacy ads, even ones that carry an 'implicit' endorsement for a side in a public debate.”

Now, six years later, CBS has agreed to run an ad by the notoriously anti-reproductive rights, anti-gay organization Focus on the Family, featuring college football star and anti-choice crusader Tim Tebow.

The network's blatantly hypocritical decision has sparked intense controversy and brought new light to the shadowy world of corporate media policy governing political or issue-advocacy commercials.

These cable and broadcast outlets seem to make the argument that only certain entities can make certain political arguments against certain figures on certain issues during certain programs. It's difficult to follow -- and perhaps that is the point. Lack of specificity provides ample wiggle room.

We do, however, know for sure that these major networks don't respond well to criticism in the form of advertising. Last year alone, CNN rejected at least two commercials critical of its own network brass and Lou Dobbs, its former immigrant-bashing host.

Then, of course, there was Glenn Beck, who last year cost his network, Fox News, at least 80 advertisers after he called President Obama a “racist.” Consequently, after filling the newly available ad time with commercials more commonly seen during a 2 a.m. rerun of Golden Girls, the conservative network was forced to respond to controversy surrounding Beck's promotion of gold investments on his program while he was also serving as a spokesman for gold investment companies that advertised during his broadcasts.

The murky subject of who can and cannot advertise could be further complicated by a recent Supreme Court decision on corporate political speech.

Last week in Citizens United v. Federal Elections Commission, the highest court in the land rejected long-established precedent, sending shockwaves throughout the political landscape when it ruled that corporations should be able to spend freely supporting or opposing candidates for office.

Corporations already run thinly veiled political advertisements designed to protect their bottom line. These ads abound, particularly on the major cable news networks and the all-important Sunday morning network political chat shows. To name but a few, big oil companies like Exxon brag about how great they are for the environment while Wal-Mart tells anyone who will listen that they really do treat their employees well. These ads, without a hint of irony, serve one purpose: sway public opinion on issues sensitive to their corporate interests in Washington and elsewhere.

How the Supreme Court's decision will affect the corporate media's policy governing corporate political advocacy remains unclear, which is precisely why I contacted the major cable and broadcast networks -- ABC, CBS, NBC/MSNBC, CNN, and Fox News -- with a few simple questions. First, will the networks announce clear policies for corporate political advertising? Second, and of equal if not greater importance, do the networks' corporate parent companies plan on taking advantage of the high court's decision by spending money for and against candidates for office?

It is no longer out of the realm of possibilities that we could one day see News Corp., Fox News' parent company, spending mountains of cash against a candidate it opposes, say President Obama in 2012, for example.

Only CNN responded to my request for comment, saying that the network is still “reviewing” the court's decision and that it was “too early” to determine the impact it may have on its advertising guidelines.

The media love to talk about transparency and accountability when it comes to politicians and the government -- they should, it's an important subject. They, too, have an obligation of transparency to the American people.

It is long past time these powerful corporate media institutions make their policies surrounding political and issue-advocacy ads readily available, publicly transparent, clear, and, most importantly, consistent.

Karl Frisch is a senior fellow at Media Matters for America, a progressive media watchdog, research, and information center based in Washington, D.C. Frisch also contributes to County Fair, a media blog featuring links to progressive media criticism from around the web as well as original commentary. You can follow him on Twitter, Facebook and YouTube or sign-up to receive his columns by email.