A judge in Southern California yesterday awarded $850 to an iPhone user because AT&T reduced his download speeds in an attempt to manage usage on its network.

The judge found in favor of Matt Spaccarelli, who filed a small claims case against AT&T last month, arguing the communications giant unfairly slows speeds on his iPhone 4’s unlimited data plan.

AT&T has some 17 million customers with “unlimited data” plans that can be subject to throttling. AT&T stopped signing up new customers for those plans in 2010, and warned last year that it would start slowing speed for people who consume the most data.

Spaccarelli said his phone is being throttled after he’s used 1.5 gigabytes to 2 gigabytes of data within a new billing cycle.