"The secretive federal court that approves spying on terror suspects in the United States has refused to give the Justice Department broad new powers, saying the government had misused the law and misled the court dozens of times, according to an extraordinary legal ruling released yesterday."

The court system is often an effective check against excess by the legislature and executive. This is one of the pieces of the system that works most of the time. Exceptions include drug related search and seizure.

Secret Court Rebuffs Ashcroft (washingtonpost.com)