So many books have been written about this. If you are genuinely curious, read The Production of Security (and justice is covered too) and other Rothbard or Hop

So many books have been written about this. If you are genuinely curious, read The Production of Security (and justice is covered too) and other Rothbard or Hoppe writings. Joe Civilian will likely seek out producers of police services and insurance services (rather than rely on his own daily gang fights), both of which will out of self-interest police each other against abusive behavior, and private courts of law have often worked exceedingly well in the short spans of history where they were permitted by oversight or accident.