What rights does a private citizen have to aid in law enforcement?
<p>Suppose you witnessed a robbery or theft from a store in the United States and saw someone running with the stolen goods, and you yell, "Stop, thief." Are you within your rights?</p>

<p>Suppose you see someone running, and the police chasing him. If you were brave or foolhardy enough to do this, are you allowed to try to trip or grab or push this person to slow him down so that the police can catch up, or would this be assault?</p>

<p>Do the above actions fall under <a href="https://en.wikipedia.org/wiki/Citizen%27s_arrest" rel="nofollow noreferrer">citizens' arrest</a>?</p>

<p>So for your first question, yelling "Stop Thief" loudly at the thief is perfectly legal (Like Yelling "Fire" in a crowded theater, it's legal if the theater is infact, on fire...  the quote implied that it was a prankster who drew amusement from the reaction of the people who took him seriously).  This may alert store employees, who have a specific kind of Citizens Arrest Power known as "Shopkeeper's Privilege" and is a reduced liability compared to Citizens Arrest.  This is also pretty basic self defense agains people who are not engaged in any physical action against you but are starting to scare you.  Suddenly shouting draws attention to you and discourages them from their behavior "I SAID DON'T TOUCH ME" being suddenly shouted in a Wal Mart is going to get notices from the immediate crowd drawn to you, and by poximate location, the person who is making you uneasy.</p>

<p>For your second question, maybe, it depends... since the cop is clearly chasing the guy, you meet the qualification to use non-deadly force in stopping the criminal (i.e. you are witnessing a person committing a crime, in this case, resisting arrest or persuit) and it would certainly be reasonably non-deadly force if you were to trip, grab, or push the fleeing suspect.   Citizens Arrest doesn't specify a minimum time to qualify, so if the officer is seconds behind, and you detain the criminal in this action until the gap is closed, it still counts.</p>

<p>The exact specifics of what you can do would depend on your location, but you are allowed to assist police. </p>

<p>Normally, the officer will tell you to help or not to help if one is there. If the officer or someone is in danger of being harmed you should obviously help though.</p>

<p>You would be here until the end of time if you went through each scenario, but the force you use to detain someone has to be reasonable under the 4th amendment, just like a real officer. </p>

<p>A citizen's arrest means that the citizen does it without the police, so if the police were there it would not be a citizen's arrest.</p>

<p>In Colorado, whose provisions on this subject are typical of U.S. law, this is governed by Colorado Revised Statutes § 18-1-707(5)-(6), with § 18-1-707(7) governing the closely related concept of a citizen's arrest without the direction of a law enforcement officer. The language of the relevant statutes is relatively straightforward and doesn't real contain any language that has special meanings in the law that are not what an ordinary reader would expect.</p>
<p>These state:</p>
<blockquote>
<p>(5) Except as provided in subsection (6) of this section, a person who
has been directed by a peace officer to assist him to effect an arrest
or to prevent an escape from custody is justified in using reasonable
and appropriate physical force when and to the extent that he
reasonably believes that force to be necessary to carry out the peace
officer's direction, unless he knows that the arrest or prospective
arrest is not authorized.</p>
<p>(6) A person who has been directed to assist a peace officer under
circumstances specified in subsection (5) of this section may use
deadly physical force to effect an arrest or to prevent an escape only
when:</p>
<p>(a) He reasonably believes that force to be necessary to defend
himself or a third person from what he reasonably believes to be the
use or imminent use of deadly physical force; or</p>
<p>(b) He is directed or authorized by the peace officer to use deadly
physical force and does not know, if that happens to be the case, that
the peace officer himself is not authorized to use deadly physical
force under the circumstances.</p>
<p>(7) A private person acting on his own account is justified in using
reasonable and appropriate physical force upon another person when and
to the extent that he reasonably believes it necessary to effect an
arrest, or to prevent the escape from custody of an arrested person
who has committed an offense in his presence; but he is justified in
using deadly physical force for the purpose only when he reasonably
believes it necessary to defend himself or a third person from what he
reasonably believes to be the use or imminent use of deadly physical
force.</p>
</blockquote>

united-states arrest citizens-arrest