Here's how the world of credit cards used to work: If a bank wanted to offer MasterCard and Visa credit cards, it wasn't permitted to offer cards from other firms, such as American Express (NYSE:AXP) and Morgan Stanley's (NYSE:MWD) Discover Card. Doesn't seem quite fair, does it?

Well, the Supreme Court didn't think so, either. It decided not to entertain an appeal by Visa and MasterCard of rulings against them in district court and the 2nd U.S. Circuit Court of Appeals in New York. The rulings found the restrictions to be anticompetitive.

The defeat for Visa and MasterCard is a victory for some other firms, such as American Express, and also for some card-issuers, such as MBNA (NYSE:KRB), which will now offer AmEx cards. It's also a victory, to some degree, for these firms' shareholders, as beefed-up business will mean beefed-up profits.

The circle of victors is even larger, though, including just about all of us who use credit cards. With more competition on the horizon, we can hope for and look for some improved terms and features in cards we're offered as various cards try to attract our business.

Learn much more about the not-so-boring world of credit cards in our Credit Center, which also offers a special deal on getting copies of your credit report so you can make sure it's correct. (Astonishingly, there's a very good chance that your report has errors on it.) The Credit Center also offers guidance on how to choose the best card for yourself -- which (dare we dream?) might even be a spiffy Motley Fool Visa card.

Read about all things credit-related on our Consumer Credit / Credit Cards discussion board. And if you're mired in credit card debt, don't despair -- you can get out of debt and build a beautiful credit score.

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Longtime Fool contributor Selena Maranjian does not own shares of any companies mentioned in this article.