CITIZEN'S ARREST - from Study Guide
A citizen's arrest is a formal arrest by a citizen has no official government authority to make such an arrest as an agent of the government. The California Penal Code gives any citizen the right to make a citizen's arrest of another citizen in three alternative situations:
1. A public offense was committed or attempted in the citizen's presence.
2. The person arrested has committed a felony, although not in the citizen's presence.
3. A felony has been in fact committed and the citizen has reasonable cause for believing the person arrested has committed it.
Why do we need a statute like this? Why do we need a "citizen's arrest"? Well, as the crime rate goes up, it becomes more and more important that good citizens come to the aid of one another in distress. Without such a statute, only government agents, such as police, would have the authority to stop a felon in progress. By creating the "citizen's arrest" statute we give ordinary citizens the authority to hold another citizen without fear of being sued for false imprisonment. Without the statute, the citizen who interfered in criminal activity would risk such a lawsuit.
Even with such a statute, the citizen still risks being sued if he/she is wrong on his assessment of the situation. Notice that the statute requires that the "public offense" be in the citizen's presence, or that the person arrested have committed a "felony," that is, a crime punishable by one year or more in state prison. Do you know which crimes are punishable by one or more years in state prison? Can you be absolutely sure the person you are arresting is the one who committed the offense? What if there were three people involved? Can you be sure which one is the one you should arrest? At the very least, a defense lawyer is going to argue that the requirements for citizen's arrest were not met and that the arrest, and any consequent seizure of contraband, were illegal.
http://www.csudh.edu/dearhabermas/citarr.htm
