With Comcast's takeover of NBC, the era of the mega-mega-merger is upon us.

For more than a century, American law has recognized the destructive power of corporate monopolies. When one company controls an entire resource, means of production, or delivery system for products, it gets an unfair advantage over competitors. It can overcharge them out of existence or drive them into bankruptcy. Since Teddy Roosevelt's presidency, our government has tried to ensure that monopolistic business practices don't destroy fair pricing and consumer choice.

Then how can it justify the merger of Comcast and NBC Universal, which the Federal Communications Commission approved on January 18? The FCC is supposed to reject any media merger that doesn't advance the public interest. But Comcast's takeover of NBC will give one mega-corporation control of too much of what we watch and how we watch it.

The deal creates not just a new media behemoth with the ability to throttle competition and stifle innovation, but a completely new model for media organizations and how they operate. Where Comcast and NBC go today, AT&T, Verizon, Disney, Time Warner, and Viacom are soon to follow. The era of the mega-mega-merger is upon us.

Comcast is already the country's largest cable and home broadband provider. The new Comcast will own production, content, and distribution for local television stations, national networks broadcasting in English and Spanish, and numerous cable channels and movie studios. One company will soon account for 20 percent of all network and cable TV viewing hours.

That should worry you.

Why? Because when one company, motivated solely by profit, can choose what news to cover and how to cover it, you may not be getting the full story. When it can exclude competing ideas or perspectives, whether for political or economic reasons, you may be denied a full hearing on the issues. And that's bad for democracy.

Want to see what this looks like in action? Search MSNBC's website for its coverage of the controversy surrounding the merger. If you look very closely, you might find a short blurb from Fort Wayne, Indiana, that mentions consumer concerns in passing. NBC Nightly News reported the deal, but anchor Brian Williams failed to mention the intense opposition to the merger or the serious concerns about it.

If a media company can keep opposing views off your TV and computer screens, you'll never know any different.

Comcast has a history of using its control over cable and the Internet to bottleneck information and cripple competitors. The company has already been caught blocking the legal file sharing of such things as barbershop quartet music and the King James Bible. More recently, it's been accused of deliberately congesting its broadband network to slow down content delivery and of raising fees for such competitors as Netflix who deliver online video to their customers. Now, with a slew of popular NBC programs in its hands and the accompanying leverage, what's to stop Comcast from doing even worse?

The FCC and the Justice Department imposed temporary conditions to make the merger more palatable, but there's not enough sugar to sweeten this rotten deal. And the conditions, inadequate to begin with, are only as strong as the FCC's willingness to enforce them. The agency's hands-off approach to the biggest media merger in recent memory isn't a good sign. There are plenty of laws against one thing or another, but without a cop on the beat, what good are they?

Monopolies are dangerous. We can expect corporations to be concerned only with padding their bottom line, regardless of the public good. But when regulators like the FCC become more concerned with pleasing corporations than protecting the public, we're all in big trouble.