Stop! Before you download that data, make sure it’s “permissible.”

In the midst of a raging debate over whether carriers should be allowed to charge more for certain types of data, or let favored developers offer users apps that don’t count against their data caps, AT&T has applied for a patent on a credit system that would let it discriminate between “permissible” and “non-permissible” traffic on its network.

Here’s how the patent application, published last month, describes it:

A user of a communications network is prevented from consuming an excessive amount of channel bandwidth by restricting use of the channel in accordance with the type of data being downloaded to the user. The user is provided an initial number of credits. As the user consumes the credits, the data being downloaded is checked to determine if is permissible or non-permissible. Non-permissible data includes file-sharing files and movie downloads if user subscription does not permit such activity.

According to the application, AT&T would be allowed to decide what other content is “non-permissible”—movies and file-sharing files are just examples—and the carrier could also levy additional fees or terminate the user’s access if they tried to access unauthorized content or exceeded their “credit allotment.”

Here’s why people find that scary and annoying: It violates a longstanding principle of the Internet, called “net neutrality,” that holds that Internet service providers should treat all the data on their networks equally. A recent ruling in Verizon’s favor has weakened the Federal Communications Commission’s ability to regulate carriers like AT&T—which sets the stage for putting a system like the one described in this patent application into place.

Netflix and other app makers have spoken in favor of net neutrality, fearing that without it, Internet service providers will try to charge them extra fees to deliver videos and other content to their users, or limit their ability to deliver their services at all.

Credit Where It’s Due—To Developers

To be clear, AT&T hasn’t been granted a patent yet. But its intentions to charge more or less for various kinds of data have been clear for some time.

Just last month, the company introduced a new “sponsored data” plan that allows some companies to pay AT&T in exchange for data usage by their apps not counting against a user’s data cap. In other words, companies willing to pay AT&T a toll will receive preferential status.

AT&T has been courting mobile-app developers with such an idea for some time. And such arrangements are popular in many developing countries, where companies like Facebook have made arrangements with carriers for their apps to be available for free, even to customers without data plans or with limited data quotas.

At the same time, it has been trying to move customers off of the unlimited-data plans it introduced to popularize smartphone usage and onto plans with data quotas. And like other carriers, AT&T has been trying to manage customers’ data usage.

In March 2012, a small claims court found AT&T was unfairly throttling a customer’s Internet speeds despite the plaintiff paying for an unlimited data plan. But even though that individual won nearly $1,000 and other mobile customers could claim similar experiences, a 2011 Supreme Court decision says AT&T does not have to allow class-action lawsuits in such circumstances, which means customers can’t rally around a policy change and must settle for small claims court for any individual problems.

The ultimate check on AT&T’s data-charging ambitions may be competition from other carriers. If AT&T became the only carrier to introduce a plan where it charged consumers differing amounts for different Internet services, it could become unpopular quickly. (T-Mobile has been particularly aggressive in competing with the likes of AT&T based on confusing contracts and plans.)

Indeed, AT&T may find more success in charging developers to let them offer data freebies to AT&T consumers instead of charging consumers directly. Mix that with the language of the patent application, and you arrive in an Orwellian world where only traffic that someone else has already paid for is “permissible.”

Lead image via Shane Curcuru on Flickr