In sharp contrast, a security officer (or any private citizen for that matter) only has probable cause to arrest for a misdemeanor if the crime was observed in his presence. Interestingly, the woman could affect a lawful misdemeanor arrest of the guy who stole her purse inside the store, assuming she saw him do it. The security officer who was standing outside where the police officer was standing, however, could not, as he did not observe the crime occur, but only saw it after the fact.

Another example: a police officer observes a suspect stumble in the parking lot while walking from a bar to his car. The police officer sees the man get in the car and start the engine. The police officer now has probable cause to stop and detain the driver even before he starts to drive. While interviewing the suspect, the officer pats down the suspect’s outer clothing for weapons (a “Terry Search”) and removes an illegally concealed handgun.

As it turns out, the suspect was sober as a jay bird. He just accidentally tripped on a crack in the parking lot. However, the police officer had probable cause to stop and detain and to conduct a pat down for the weapons based upon his reasonable suspicion.

Again, in contrast, the security officer who made the same observation of the “stumble” would have been wrong about the suspect’s sobriety. Thus, any detention would have been illegal, simply because the misdemeanor thought to have been committed in the security officer’s presence – attempted driving under the influence – was not, in fact committed. Thus, the pat down search of the weapon was not proper, and the evidence was thus illegally obtained. Any detention flowing from the initial stop was improper, and the evidence obtained could be suppressed. Ironically, the suspect could even sue the security officer for false imprisonment.

In regard to felonies for both private persons and police officers, both a private person and a police officer may arrest a person who has committed a felony although not in the presence of the officer or the private individual. In the third analysis, both the officer and the private individual may arrest a person if the officer or the individual has reasonable cause for believing the person arrested has committed a felony. However, for the private individual the arrest must be made when a felony has actually been committed and the private person has reasonable cause to believe the person arrested has committed the felony. For the police officer, the police officer only needs to have probable cause to believe that the person arrested has committed a felony whether or not a felony has actually be committed. Consequently, against the police officer’s authority to arrest is broader than the private individuals.