Police responded to an anonymous tip that two black males were handling a gun in a black Ford Focus in a Denny's parking lot. The first two officers to show up found only one black Ford Focus in the parking lot, and there were two black male occupants, but they didn't actually see any gun. They ordered the occupants at gunpoint to show their hands, and the driver complied. Mosley (the passenger) did not; he began making movements consistent with either retrieving a gun from under the seat or hiding one under the seat.
The officers (who it seems were standing WAY to close to the car) started kicking the car to "shock" Mosley into compliance. Eventually he did put his hands up, so they opened the door and ordered him out. He wouldn't get out of the car, so they dragged him out and cuffed him. Later, they checked under the seat where he had been sitting and found a gun. Mosley was charged with being a felon in possession of a firearm. After the district court denied his motion to suppress, Mosley entered a conditional guilty plea and appealed.
Mosley's argument is that the police did not have justification for stopping him in the first place, and that the amount of force used during the stop converted the stop into an arrest for which the police lacked probable cause.
One of the officers testified to a history of shootings and other crimes at that particular Denny's, and the Tenth Circuit sort of hinted that based on all of that and the anonymous tip the officers had reasonable suspicion. But the court took a different path to actually deciding this case.
Someone is seized for Fourth Amendment purposes when one of two things happens: 1- the police attempt to stop them by means of a show of authority and the person submits to their authority, or 2- the police apply physical force to a person to effect the seizure. In this case, that means that although the driver was seized when the officers started giving orders at gunpoint, Mosley was not. Rather than put his hands up as ordered, he did the exact opposite. By the time Mosley did put his hands up, his furtive (I'd have said threatening, but the court said furtive) movements had already provided justification for the stop even if it hadn't been justified in the first place (the court made it clear that it was not deciding that the stop wouldn't have been justified, but only assuming that for the sake of argument).
As far as Mosley's second argument, that the amount of force used against him converted the stop to an arrest... he misses the point. During a Terry stop, officers are permitted to use force to ensure their own safety and to "maintain the status quo" during the stop. Under the right circumstances, that can include pointing guns at someone or forcing them to the ground. The important question is whether the facts available to the officer at the moment of seizure (in this case, the moment where Mosley finally put his hands up) would make a reasonable person believe the action taken by police was appropriate. Given all of the information available to the officers at the time of this stop, conducting the initial stop at gunpoint was reasonable.
The court chose not to decide whether or not everything the police did after that (kicking the car, dragging Mosley out of the car, etc...) converted the detention to an arrest because it doesn't matter. By then, because he had been failing to comply with lawful orders, the police had probable cause to arrest him for violating the Kansas statute for Interference With Law Enforcement. So even if dragging Mosley to the ground converted the detention to an arrest, the arrest was justified.
Since Mosley's Fourth Amendment rights were never violated, the gun was not the fruit of an illegal stop. The lower court's decision was affirmed, and Mosley's conviction upheld.