The recent lawsuits filed against Three Sisters Irrigation Manager Marc Thalacker are centered around a "citizen's arrest" conducted by Thalacker in April 2010 during the McKenzie Canyon piping dispute.

This case raises the questions: Is there such a thing as a citizen's arrest? Is it legal? What are the risks?

In fact the concept of a citizen's arrest is embraced by many countries around the world and by all the states in the U.S. except North Carolina. While the concept remains largely the same in each state, the details vary widely - from allowing lethal force to expressly excluding deadly intervention.

Historically, in Anglo Saxon law in medieval England, citizen's arrests were an important part of community law enforcement. Sheriffs encouraged and relied upon active participation by able-bodied persons in the towns and villages of their jurisdiction. From this legacy originated the concept of the posse comitatus, which is a part of the American legal tradition as well as the English.

In Oregon, the Oregon Revised Statutes, ORS133.225, state the following: The crime must actually be committed in the presence of the citizen and the citizen must reasonably believe that a crime was committed. The citizen must advise the person being arrested clearly that a) he is under arrest and b) what the charge is. The citizen must then a) take him into custody and b) immediately deliver him to a law enforcement officer or to the court.

While allowed in certain situations by the statutes (ORS 161.190-275), the details concerning the use of physical force and restraint are complex and numerous. In a 2007 article in The Southern Oregon Mail Tribune, Lt. Brian Powers of the Oregon State Police explained the process this way: "Basically, you have the same authority (to arrest) that I do, it's just easier for me because I've got the tools to get people to court. You've got to be careful, though. We've got insurance that covers us. You don't."

In the same article Jackson County District Attorney Mark Huddleston says, "In other words, the statute does NOT say that Citizen A can lawfully arrest Citizen B merely because 'B' is annoying 'A.' Performing a citizen's arrest on someone for committing a minor offense could result in a false arrest charge," says Huddleston.

The crime, either a misdemeanor or a felony, must be one which could incur potential jail time - such as drunken driving. In the U.S., strict liability laws still apply (such as infringement of civil rights), and include potential prosecution of the citizen making the arrest for false arrest and civil penalties if the citizen's arrest is made using false or misleading information.