The school says it will honor its contract and pay Rob O'Neill's USD 28,000 speaking fee.
The university cited "unforeseen circumstances" in canceling Monday's speech by O'Neill, who has said he killed bin Laden during a raid on his Abbottabad compound in May 2011. O'Neill was arrested for DUI in Butte early Friday, after he was found sleeping at the wheel of a running vehicle at a convenience store.
O'Neill pleaded not guilty to the misdemeanor charge. He released a statement saying he had taken a prescription sleep aid and had not been drinking.