Minarchism is the political philosophy that advocates the minimum government necessary to ensure social order. In general, minarchists support government providing a legal system including police and judges. Beyond this, there is often disagreement about what the government's minimal role should be, with some including roads and natural resources, but others holding only to police and a court system.
One popular form, defended by Robert Nozick in Anarchy, State, and Utopia, is the night-watchman state, which would have only courts, police, and a military.