In my youth, I used to catch shoplifters in a bad area. Occasionally, the miscreants would file a law suit, naming me and the Corporation I worked for, especially when the crimes were charged as (Felony) burglary or robbery if they tried to murder us, instead of misdemeanor petty theft. In most cases my employer would just ignore the suits, and stall until the evil-doer had a criminal court date, which usually ended the lawsuit. (These kind of crimes are routinely plead out in California) On one happy occasion, an individual masquerading as an attorney, but in fact a pseudo-paralegal, came to my work place and tried to threaten us to compel us to drop the case. We recorded him, and arrested him on the spot. The local PD was very happy to take him into custody. For a private citizen who uses force, I suggest using the "Lone Ranger" approach: Leave without giving your name (To avoid the gratitude of the Police...)