a definition of "to police" from the Latin meaning "state" and Greek "city" is

"Regulation and control of the affairs of a community, especially with respect to maintenance of order, law, health, morals, safety, and other matters affecting the public welfare."

Many of the Travelling People (or Tinkers as they would be referred to by the settled community) would perceive themselves as both "outsiders" to and "victims" of an organization that policed people who did not conform to the state's regulations

as in Ewan McColl's "Freeborn Man of the Travelling People" from the Radio Ballad "The Travelling People"