Morrow described the lawsuit as a "last resort" and an effort to protect free speech.
"I am a public official," Morrow said. "I want to hold a public town forum, and I am unable to do so because of the threats, coercion and intimidation of those who disagree with the message."
Sponsored by Morrow, the scheduled meeting, titled "The Illegal Immigration Crisis," was scheduled to include former San Diego mayor and radio talk-show host Roger Hedgecock as emcee, Colorado Congressmen Tom Tancredo, Minuteman Project founder James W. Gilchrist, attorney and author Madeleine Cosman, and former U.S. Attorney Pete Nunez.
Morrow's meeting was to have focused on how illegal immigration affects health care, homeland security, education, the economy and the environment, according to a flier distributed by the senator's staff.
Morrow said a state appeals court ruled in 1998 that canceling an event because of threats of violence from opponents of the event amounted to an unconstitutional prior restraint on free speech called a "heckler's veto."
Lepiscopo, Morrow's attorney, said the district's remedy to address safety concerns is to have enough police officers present, not to cancel the event. Morrow said Monday that police have told him they could provide adequate security for the event.
"When somebody says, 'Hey, if you don't shut up' or takes action to shut you up and not say your piece under threat of disruption or violence, that cannot be tolerated, not in the USA," Morrow said.