In California, the following Penal code sections provide strict construction for arrests by anyone: 837. A private person may arrest another: For a public offense committed or attempted in his/her presence. When the person arrested has committed a felony, although not in his presence. When a felony has been in fact committed, and he or she has reasonable cause for believing the person arrested to have committed it. 839. Any person making an arrest may orally summon as many persons as he/she deems necessary to aid him/her therein. 841. The person making the arrest must inform the person to be arrested of the intention to arrest him, of the cause of the arrest, and the authority to make it, except when the person making the arrest has reasonable cause to believe that the person to be arrested is actually engaged in the commission of or an attempt to commit an offense, or the person to be arrested is pursued immediately after its commission, or after an escape. The person making the arrest must, on request of the person he is arresting, inform the latter of the offense for which he is being arrested. 844. To make an arrest, a private person, if the offense is a felony, and in all cases a peace officer, may break open the door or window of the house in which the person to be arrested is, or in which they have reasonable grounds for believing the person to be, after having demanded admittance and explained the purpose for which admittance is desired. 845. Any person who has lawfully entered a house for the purpose of making an arrest, may break open the door or window thereof if detained therein, when necessary for the purpose of liberating himself, and an officer may do the same, when necessary for the purpose of liberating a person who, acting in his aid, lawfully entered for the purpose of making an arrest, and is detained therein. 846. Any person making an arrest may take from the person arrested all offensive weapons which he may have about his person, and must deliver them to the magistrate before whom he is taken. 847. (a) A private person who has arrested another for the commission of a public offense must, without unnecessary delay, take the person arrested before a magistrate, or deliver him or her to a peace officer. (b) There shall be no civil liability on the part of, and no cause of action shall arise against, any peace officer or federal criminal investigator or law enforcement officer described in subdivision (a) or (d) of Section 830.8, acting within the scope of his or her authority, for false arrest or false imprisonment arising out of any arrest under any of the following circumstances1) The arrest was lawful, or the peace officer, at the time of the arrest, had reasonable cause to believe the arrest was lawful.(2) The arrest was made pursuant to a charge made, upon reasonable cause, of the commission of a felony by the person to be arrested.(3) The arrest was made pursuant to the requirements of Section 142, 837, 838, or 839. Since police are comprised of private citizens... it applies to them as well. The are not above the law and should not be beyond reproach either.