According to the Penal Code Section 834, “An arrest is taking a person into custody in a manner authorized by law.” Penal Code Section 834 also goes on to state that, “An arrest may be made by a peace officer or by a private person.”
Penal Code Section 837 specifies the conditions under which you, as a private person, may make an arrest. “A private person may arrest another.
1. For a public offense committed or attempted in his presence.
2. When the person arrested has committed a felony, although not in his presence.
3. When a felony has been, in fact, committed and he has reasonable cause for believing the person arrested to have committed it.”
In making your decision to arrest someone, you must first determine whether the offense is a felony or a misdemeanor.
EXAMPLE OF A MISDEMEANOR OFFENSE
If you observed a person picking up a rock and throwing it through a plate glass window, that person could be arrested. Breaking a window is a misdemeanor offense and you know that he committed the offense because you saw him do it.