Justice O'connor, in a concurring opinion in Florida v. Riley, questions whether a police helicopter flying at 400 feet is in fact in airspace normally used for travel by the public. Respondent Riley's expectation that the public and the police would not travel over his property at such altitudes in helicopters was reasonable, observed Justice O'Connor. Relying on Katz v. United States, Justices Brennan, Marshall, and Stevens dissented and said they would have suppressed the marijuana found in Riley's greenhouse as the result of the helicopter observation flight. The article includes a brief history of helicopters used in police work and details Federal Aviation Administration regulations on helicopter flights over congested and non-congested areas.