As a general rule, a police officer may approach and contact any person anywhere that the officer has a legal right to be, and engage that person in a conversation. All law enforcement officers are taught in the police academy that there are three types of officer/citizen encounters.
The first is consensual encounter which does not require reasonable suspicion or probable cause so long as a “reasonable" person would feel free to leave or decline to speak to the police. The second is the investigatory stop which enables the police to briefly detain a person for further investigation. It requires that the officer has reasonable suspicion to believe is involved in criminal activity. Third is arrest and probable cause must exist.
Encounters with the police can be a friendly “hello, how are you" to one that rises to an arrest. It is a case by case basis and analysis to ascertain whether the encounter was permissible based on consensual encounter. Some pertinent facts are: the meeting was brief and not intrusive; no guns were drawn by the officer; the officer’s stance (body, car) did not block or impede the path of the individual if he/she walks away; few and brief questions; no handcuffs were used.
There are many scenarios and an effective criminal defense attorney will investigate and review every detail of the confrontation. I recently won a motion to suppress the evidence on a second DUI because I proved to the court that the officer lacked any probable cause to stop my client. I also successfully proved that there was no valid consensual encounter. The case was dismissed in its entirety.
Officers are trained that they should attempt to abide by and generally not to: block the person’s path, either by your person or car; speak in normal tone of voice rather than giving commands, request rather than demand to speak to a person’s; avoid pointing or even drawing their gun; avoid intimidating gestures, movements or commands. Any showing of authority will likely not be deemed as a “friendly" encounter.
Here are just some examples: Stop! Police! = detention vs. “May I speak to you" or “Got a minute" = Consensual; Driving alongside or behind a pedestrian or the car (without commands, sirens or red lights) = Consensual v. “Effecting overhead police lights or directing them to stop on the side of the road" = detention.
Within the scope of a consensual encounter, the police officer may request for ID/Driver’s license and run for warrants etc. If you retain this ID without giving it back, some case laws have deemed that to be detention but once you have conducted the necessary cursory information and return it to the person, it is merely consensual.
It may seem shocking to some and even unbelievable, but if you are approached by a police officer and there is no showing of authority: guns, overhead lights of the patrol car are lit up or commands to stop but merely a statement of “you got a minute," you can chose to walk away. I realize this is inherently “unnerving" but under the law, unless the officer has probable cause to stop, citizens are free to leave.