The Citizens Against UFO Secrecy (CAUS) sued the U.S. federal government and the State of Arizona Wednesday, alleging that the government had broken its Constitutional obligations by refusing to protect U.S. citizens from a "clandestine invasion" from outer space.

In a press release, CAUS Executive Director Peter Gersten called the government's lack of official response to the UFO phenomenon an "outrageous" evasion of its responsibilities to the public.

"It's outrageous that this threat is continually ignored," he said. "I can prove in a court of law, and beyond a reasonable doubt, that we are in contact with another form of intelligence. More importantly, one aspect of this contact poses a threat to our safety."

CAUS has sued the government six times in the past in order to obtain secret UFO materials. However, despite the UFO group's dogged use of the Freedom of Information Act in pressing its claims against various government bodies -- including the Central Intelligence Agency, National Security Agency and the defense department -- the results have been disappointing. Agencies either denied having any relevant documents or else admitted their possession of such materials, but refused to release them on grounds of national security.

As a result, CAUS says it will now only resort to the Freedom of Information Act "under special circumstances," a change in legal tactics that possibly prompted the new lawsuit..

Gersten said Arizona will serve as a test case for possible wider legal action, saying that "Arizona is definitely a targeted area for the clandestine intruders" behind such events as the 1975 Travis Walton disappearance and the 1997 "Phoenix lights."

If Gersten's motion succeeds, CAUS will seek to compel both state and federal governments to "initiate an immediate study and investigation" into the nature of UFO phenomena.

Gersten will appear on Art Bell's popular UFO-oriented radio program "Coast to Coast" Wednesday night to discuss the suit.