"Political power comes out of the barrel of a gun," Mao Zedong infamously said. This was true in the civil wars Mao fought and was too often true in the lawless way he oppressed his people. It is generally true in the anarchy of international relations, and would be true for individuals if they lived without law. People of practically all political stripes agree that the problem of force is one of the most important political problems, and I suspect most would agree with me that it is the most important problem. It is also the central problem addressed by the law.
We can start to understand both law and politics by understanding a bit of the highly evolved common law in a situation that lies close to anarchy: the obligatory gunfight in the old Western movies. With my habitual lawyerly habit of "issue spotting," I've noticed how the good guys in these old Westerns almost always, if often barely, follow the common law of self-defense. The white hat waits until the villain reaches for and grabs his gun -- showing intent to shoot -- before he grabs his. This heroic habit illustrates one of the great summaries of the substance of the common law -- namely "thou shalt not initiate force" -- or, in a more peaceful setting, fraud. If one had to summarize the substantive parts of the common law into one sentence, that would be it -- "thou shalt not initiate force or fraud."
This is not to say that one can logically deduce all important parts of law or politics from such a principle -- a common mistake of ideologists. One can no more deduce the content of the law from simple principles than one can deduce the specific sequence of an animal's genetic code from any few simple rules. Both, in mathematical terms, have an irreducible Kolmogorov complexity and any of these kinds of summaries are quite lossy. But it does turn out that almost all of the substantive common law operates in close proximity to that libertarian principle.
There are some other good ways to summarize the common law. "The right to be left alone" is a good brief description of our rights under criminal, tort, and property law -- in other words these are generally systems of negative rights rather than of positive rights to compel another person's affirmative effort. Since we often don't really want to be left alone we also have contract law, which generally operates according to the principle of "keep your promises", inheritance law, "respect a dying man's wishes, and if you don't know them he meant to leave his wealth to his family," and so on.
Back to our movie: let's say we come into the theater just as our hero is firing his gun. He has already drawn his gun while the villain is still bumbling around. Our hero shoots first and our villain crumples to the ground. If we didn't know this was an old Western, where the hero always draws faster despite drawing second, a reasonable guess would be that our killer was able to shoot first because he drew first, and is thus a murderer.
Only in full context do we see the initiation of force and a response to it. In isolation, the response to force is often indistinguishable from the initiation of force. We often can't know for sure whether an act of coercion is an unlawful initiation of force or a lawful response to it until we've seen the entire film (and in modern Hollywood, not even then, though I digress). Or, to change metaphors and introduce a bit legalese, we often don't have probable cause to believe someone has initiated force until we've assembled some pieces of the puzzle. Learning to some even greater degree -- clear and convincing evidence in some private cases and beyond a reasonable doubt in criminal cases -- who initiated force requires even more pieces.
Furthermore, to achieve justice -- to deter, to exact retribution, to make whole the victim, or to heal the sick criminal, whichever one or more of these we take to be the goal of justice -- we must almost always respond to force with force. Taken in isolation that response will itself look like an initiation of force. Furthermore, to gather the evidence we need in most cases to achieve sufficient high levels of confidence -- whether balance of the probabilities, clear and convincing evidence, or beyond a reasonable doubt -- we often have to initiate force with third parties -- to compel them to hand over goods, to let us search their property, or to testify. If politics could be deduced this might be called the Central Theorem of Politics -- we can't properly respond to a global initiation of force without local initiations of force.
Again keeping in mind that we are leaving out many important exceptions and details, we might summarize good legal procedure -- and more abstractly, the way a good political system should respond to force -- as follows:
(1) An initiation of force might have occurred
(2) Learn enough, without responding with force of our own, until we have probable cause to believe an initiation of force has occurred.
(3) Respond with our own force in order to arrest the persons, valuables, and evidence involved, and engage in the trial(s) and other procedures necessary to convince those most highly knowledgeable about the case, and if it is important enough the world generally, that an initiation of force indeed occurred.
(I'm neglecting, of course, the controversial issue of preventing force by initiating force -- in the international context by invading Iraq to prevent supposed weapons of mass destruction, in the individual context by capturing a terrorist before they've actually committed an act of terror. This is dangerous territory that goes beyond the general responsive workings of legal procedure, and will be hopefully a topic I address another day).
In Hollywood our hero has a quick eye and thereby instantly achieves probable cause that our villain has reached for his gun and is threatening to fire. In reality, the evidence is usually far more dispersed and we must be far more careful, lest our supposed response to force actually be an initiation of force.
Since force is the central problem of politics, a political system, whether proposed or real, that cannot distinguish an initiation of force from a proper response to force -- that cannot distinguish an arrest of a person from a kidnapping, an arrest of goods from theft, and so on -- is worth less than the paper it's written on. And if it merely waves its hands and invokes the magic of "the government" or "the market" to solve all such problems, it is extremely lame -- and quite at odds with how our highly evolved common law legal procedures actually work. The common law does not, as the law of self-defense suggests, necessarily require "the government" for a legally forceful response to force. But neither, as we shall now see, do its legal procedures operate in any way resembling the laws of economics in a voluntary market.
Recall our Central Theorem of Politics -- we can't properly respond to a global initiation of force without a local initiation of force. We could deduce, if law could be deduced, that legal procedure thus might be full of local initiations of force -- and in fact it is. Legal procedure, in sharp contrast to good substantive law, does not involve merely negative rights "to be left alone," but in addition is full of positive rights. It is full of procedures for interfering with persons and property, both with the defendant who might have initiated force and with some third parties who are not accused of initiating force. The right to sue, for example -- necessary for the enforcement of any private substantive right -- is a bundle of positive rights that usually includes the right to compel a jury to sit and the right to compel witnesses as well as a right to compel the the alleged initiator in various ways. Proper response to the initiation of force would be extremely and quite unreasonably hobbled without these coercive mechanisms, these positive rights of legal procedure. And unless the disputing parties have arranged things ahead of time, the exercise of jurisdiction by our "responder to force," the court, is involuntary for at least one of them. Often the responder has to be backed by some kind of police force, or an extreme cases even an army, if justice is to be achieved. It is preventing the abuse of all this power -- including figuring out ways to minimize the power without overly reducing our ability to resond to force -- that is the central problem of politics.
Ideological purists can whine all they want about the supposed injustices of the coercion inherent in legal procedure, but "thou shalt not initiate force" is merely a useful summary of the substantive common law and in no way provides a useful summary of the procedural common law, much less a principle for its operation. The job of legal procedure -- and of good politics generally -- is to respond to initiation of force with its own local initiations of force in order to achieve justice: to punish the initiator of force and to provide restitution to his victim. Whatever form this response might take -- whether a nation-state making war or enforcing law through its courts, or parties who have previously agreed resolving their dispute through a private court, or a shopping mall security guard arresting a shoplifter, or our quick-draw Western hero -- whatever form response to force may take, it is crucial that law carefully defines the proper ways for making such responeses and that we put limits on these methods to prevent abuses. It's also crucial to realize that any princples by which we might do so will tend to be very different than those of the substantive law being enforced.