A group of "BASE jumpers" argued in federal court Friday that the National Park Service doesn't have the authority to regulate the airspace over Lake Powell.

The nine parachutists were charged with violating a Park Service rule in 1995 when they jumped off a 400-foot cliff at Lake Powell.That rule prohibits the delivery or retrieval of a person or object by parachute, helicopter or "airborne means" except in emergencies or with a permit.

But in a motion to dismiss the case, attorney Fred M. Morelli argued on Friday that the entire surface of Lake Powell is a designated landing zone where the air space is governed by the Federal Aviation Administration.

There is no FAA prohibition against parachute jumping at designated landing zones, Morelli said, and the Park Service cannot preempt the FAA when it comes to the regulation of "navigable fair space." Also, he said it's discriminatory to allow some aircraft to land on Lake Powell while banning parachutes.

U.S. District Senior Judge Bruce Jenkins was clearly intrigued by the pre-emption argument, telling Assistant U.S. Attorney Wayne Dance, "I'm interested in finding out who gets to say: The Park Service or the FAA?"

If the answer is the FAA, then the charges against the nine parachutist would be in legal jeopardy because they were based on Park Service authority.

Dance contended the Park Service rule isn't intended to regulate air space but rather to protect visitors engaged in activities on and around the lake. Calling the landing zone argument a "red herring," Dance said in the absence of any FAA regulation governing BASE jumping at Lake Powell, the Park Service rule is the governing law.

BASE jumping is an extreme sport practiced by parachutists who leap off buildings, antennae, spans and earth forms. Charged in the Lake Powell case are William Oxx, Jonathan Oxx, Martin Tilly, Christopher Berke, David Katz, Steve Mullholland, John M. Henderson, Aaron M. Brennan and Michael Kvale.

Jenkins dismissed the charge against them last year after concluding that parachutes are similar to non-powered aircraft, which are allowed to land at Lake Powell.

While not specifically holding that parachutes are aircraft, Jenkins accepted the BASE jumpers' assertion that their air foils or canopies were navigable like aircraft.

However, the 10th Circuit Court of Appeals reversed Jenkins and sent the case back for trial, saying, "A parachute by any other name is still a parachute, and delivering a person by parachute is prohibited."

Despite the appeals court ruling, Morelli continued to argue the point on Friday. "These are no more parachutes than an automobile is a horseless carriage," he said.

According to Morelli, the BASE jumpers' parachutes are, like any aircraft, a contrivance to navigate in the air. He said the FAA recognizes parachuting as an aeronautical use that is allowed at designated landing zones (airports) when compatible with other flight activity.

Dance said BASE jumping is not compatible with other activities at Lake Powell. He also noted that it puts a strain on Park Service resources because law enforcement and medical personnel are brought into play "when these activities go awry."

In the case before the court, William Oxx required emergency help and was hospitalized when he crashed into a hillside.

Jenkins asked the two lawyers to submit written arguments on the pre-emption issue and also asked them to provide him with details about FAA regulations on parachutes at landing zones within the next month.

He also asked Dance for information on the permit exception in the Park Service rule. For example, the Park Service issues permits to hundreds of BASE jumpers who leap off the 876-foot-high span at Fayeteville, W.Va., on "Bridge Day" each year. The event drew 150,000 spectators last year, Morelli said.