When police officers have the reasonable suspicion necessary to justify an investigative stop, the suspect is not free to walk away, and officers may use reasonable force to prevent the suspect from doing so. Physically grabbing suspects after lawfully commanding them to stop is a relatively nonintrusive means for officers to encourage compliance. An escalation of physical restraint is only permissible in response to a subject's escalation of resistance. Placing a suspect inside a police vehicle is another level of restraint that could affect the reasonableness of an investigative detention. In U.S. v. Bradshaw (1996), the U.S. Court of Appeals for the Sixth Circuit affirmed the trial court's denial of the motion to suppress evidence police obtained in the course of a detention inside a police vehicle in an investigative stop. Although noting that detention in a police car may rise to the level of an arrest, the court held that it does not automatically do so. Although deadly force is not a viable option for enforcing an investigative stop, officers may frequently display firearms during such stops as a means of discouraging aggressive behavior by potentially dangerous suspects; however, courts generally view the display of weapons by police as a factor that "increases the seriousness of the stop"; thus, the display of weapons should be justified by the suspect's aggressive behavior. Although the handcuffing of a suspect is one of the most common symbols of an arrest in the United States, most courts have declined to adopt a blanket rule that using handcuffs to restrain a person under all circumstances is tantamount to an arrest; handcuffs are appropriate when officers have a reasonable suspicion that suspects have been involved in a violent crime or the suspect displays dangerous aggression. As a general rule, any use of force that is not justified by the facts and circumstances will be viewed by the courts as converting the stop into an arrest, which, in the absence of probable cause, would be unconstitutional. 32 footnotes