The Federal Aviation Administration has blocked plans for a small drone to deliver the game football for the University of Michigan kickoff Saturday against the University of Utah before a crowd of about 110,000 fans.

The FAA's move is the latest example of flight regulators blocking the use of small drones for commercial purposes, despite the questionable legal authority for them to do so. The drone, built by Ann Arbor-based SkySpecs, was supposed to participate in a pre-game program of the American football game to celebrate the University of Michigan's 100-year anniversary of its aerospace-engineering program.

Bloomberg News said that after the FAA explained its rules, "the school backed down."

Hobbyists may fly the small drones under guidelines adopted by the agency, and they must be flown away from crowds. Both Google and Amazon are testing drone-delivery programs for commercial purposes, but federal law bans those business models for now.

The FAA has maintained since at least 2007 that the commercial operation of drones is illegal. A federal judge ruled in March, however, that the FAA enacted the regulations illegally because it did not take public input before adopting the rules, which is a violation of federal law. Flight regulators have appealed the decision, maintaining that commercial applications are still barred.

The agency has promised that it would revisit the commercial application of small drones later this year, with potential new rules in place perhaps by the end of 2015. But for now, the agency is taking a hard line against the commercial use of drones, and it's unclear whether that policy would change.