What is the practical difference between a state (government) and any other institution in society? The license to detain (coercively restrain, by threat or physical force) a person indefinitely without just cause, I’d say. Let’s think it through.
“Just cause” is a relative concept. It means different things in different contexts. In the context of voluntaryist legal theory (the only logically and ethically valid kind of legal theory, methinks), someone has just cause to temporarily detain another person when that person is in the process of committing a crime.
Crimes are not simply the violation of a rule, rather, crimes are those behaviors which cause injury to another person or their property. Crimes are the result of aggression. All behaviors which are not criminal, are liberties. I explore this in more detail in “Two Types of Laws; The Voluntaryist Perspective on Politics“. During the commission of a crime, a person may be justifiable detained. It’s a matter of self defense.
May a person accused of a crime after the fact be detained? That depends on whether or not they actually committed the crime. Even in a free society, people accused of crime will be detained when the preponderance of evidence is such that the person or institution attempting detention is confident of guilt. After all, they are liable for injury if their detention is without just cause. Arrest someone who, it turns out, is innocent of any wrongdoing, and you’ve committed the crime of kidnapping and false imprisonment yourself. Restitution is owed.
States routinely detain people not on criminal grounds herein defined, but for the violation of a rule. This is patently unjust. Further, states protect their officers on the basis of qualified immunity, as well as itself on the basis of sovereign immunity. Only states enjoy these privileges, which protect its officers and its stakeholders from liability for wrongdoing.
Regular people, churches, charities, businesses, corporations, et cetera are far less likely to answer in the affirmative with sufficient follow through to the question, “Am I being detained?” They have their own financial interests to protect. For this reason, and many others, states are uniquely positioned as institutions in society with a license to detain a person indefinitely without just cause.