Isegoria

Until the modern era, courts had little power to enforce their authority, so they instead declared criminals outlaws:

When it was originally imposed in the Middle Ages, a sentence of outlawry was essentially a death sentence that the court did not believe it could immediately enforce, largely because the person was nowhere to be found. An outlaw was a person whom it was illegal to give any food or shelter, and whom it was legal to kill on sight as one might a wild animal. The pronouncement caput gerat lupinum, “Let his be a wolf’s head” (gotta be a lycanthropy storyline in there somewhere) set someone outside the bounds of civilized society. The theory was that a person who failed to show up to answer a felony charge was admitting their guilt.

Still, by the modern period, the definition of outlawry had shifted somewhat. Sir William Blackstone, perhaps the most famous English jurist in history, had already observed by the late-eighteenth century that while outlawry was still a potential sentence for criminals, it no longer permitted an outlaw to be killed at will. Rather, it permitted anyone to arrest them for prosecution and retained the penalties for aiding an outlaw.

The spread of civilization and thus of court authority reduced the need for declaring someone an outlaw, but a world full of supervillains might still see the need:

If the Joker is threatening to drop a bus full of school kids off a bridge, yeah, Batman can do whatever, because deadly force is justified in preventing the deaths of others. But if the Joker is between capers, private actors, like most superheros, can’t go after them without exposing themselves to civil and criminal liability for wrongful death, impersonating an officer, false imprisonment, excessive force, etc. But if the supervillain were declared to be an outlaw, hey, all bets are off. Go nuts.

Of course, the whole notion of outlawry is completely incompatible with modern concepts of due process:

For starters, declaring someone guilty because they failed to show up for trial violates just about every procedural standard it is possible to name, chief of which is the presumption of innocence, an important civil right enshrined in Coffin v. United States, 156 U.S. 432 (1895), which held: “The principle that there is a presumption of innocence in favor of the accused is the undoubted law, axiomatic and elementary, and its enforcement lies at the foundation of the administration of our criminal law.”

So that’s probably out. But trial in absentia is probably out too, at least without some changes being made to the law. Federal Rule of Criminal Procedure 43 requires the presence of the criminal defendant, and Crosby v. United States, 506 U.S. 255 (1993) makes it pretty clear that a criminal who is arrested but escapes or absconds before trial cannot be proceeded against until he appears in court. It may be possible that a trial might be permitted to continue if a defendant is there at the beginning and then voluntarily leaves (see United States v. Lawrence, 161 F.3d 250 (4th Cir. 1998)), but simply bringing charges against someone and going to trial without them would probably not be permitted under current law.

Still, if I were the prosecutor, I’d make the argument that a supervillain that law enforcement is unable to apprehend but who damn well knows about the prosecution is a different case than your standard, underprivileged, uneducated, minority offender that the legal system is right to try to protect from being railroaded or lynched inside the courthouse. One might even limit the definition of “supervillain” to “one who possesses powers or abilities so far in excess of ordinary human beings that forcefully apprehending them would either be impossible or almost certainly cause significant loss of innocent life.”* This might constitute a violation of equal protection, but there’s a good case to be made that such an approach would survive strict scrutiny, in that it is 1) directed at a compelling governmental interest, 2) narrowly tailored, and 3) the least restrictive means of accomplishing said interest. Given that a challenge of this sort would probably be first attempted against a notorious villain the cops are unable to apprehend, and that a sentence of outlawry would manifestly assist both superheros and traditional law enforcement in their efforts against said villain, the pressure to find some way of carving out an exception would be pretty significant. Then again, hard cases make bad law, so whether or not this is a good thing remains to be seen.

One cynical commenter notes that slapping the terrorist label of a super-villain should be close enough to declaring them outlaw.

The options for supervillain real estate look shockingly similar to the options for a libertarian state:

I. Unclaimed Land

You may be surprised to learn that there are a (very) few places left on Earth that are unclaimed by any sovereign nation. Perhaps the most reasonable is Bir Tawil, a 770 square mile stretch of desert between the borders of Egypt and Sudan. There isn’t a whole lot there, but at least it’s relatively close to more interesting places, and the neighbors are probably too concerned with their own problems to care about a supervillain moving in next door.

The other major possibility is Marie Byrd Land, which is part of Antarctica. At over 620,000 square miles it’s comparable in size to Mongolia or Iran and would be the 19th largest country in the world if it were one. While no countries lay claim to this land, the Antarctic Treaty of 1959 expressly prohibits “any measure of a military nature, such as the establishment of military bases and fortifications.” Although a supervillain, as a private entity, would not be bound by the treaty, that language might provide the basis for joint military action to oust a supervillain operating out of Antarctica. The treaty does state that “Antarctica…shall not become the scene or object of international discord,” but it is doubtful that such language would give the signatory nations much pause before launching the cruise missiles.

A third possibility is purchasing an island from a sovereign nation, but it may be difficult to convince the owner to give up all claim to the island. Ordinarily private islands like Richard Branson’s Necker Island still remain the sovereign territory of a nation (in that case the British Virgin Islands). But there are many impoverished island nations, and an enterprising supervillain may attempt to strike a Faustian bargain for sovereign territory.

Unfortunately, being stuck on land makes a supervillain an easy target, and unless the supervillain can gain international recognition and thus sovereign status, the base is likely to be attacked without legal repercussions. The main benefits here would be isolation and a lack of direct government oversight, not a legal shield against reprisal.
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II. The High Seas

If no land is available or if mobility is a concern, then a supervillain can consider the oceans. The primary governing treaty is the United Nations Convention on the Law of the Sea. This gives some freedoms, including the right to build artificial constructs, but it also prohibits claims of sovereign territory, so a supervillain probably could not create a new floating nation. Still, as long as he avoided making territorial claims, there doesn’t seem to be any legal reason that a sufficiently large floating construct couldn’t just sail around forever.
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But there are other problems for a seafaring supervillain, most particularly the lack of a national flag (presuming that a supervillain would not long be able to fly even a flag of convenience). Article 110 provides that a warship may board a foreign ship on the high seas if “there is reasonable ground for suspecting that…the ship is without nationality.”
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III. Outer Space

Outer space probably represents the best bet for a supervillain. Although the supervillain and his or her base would not have much in the way of direct legal protections in space or on the Moon, he or she would be protected indirectly by the Outer Space Treaty. The OST bans placing “in orbit around the earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install[ing] such weapons on celestial bodies, or station[ing] such weapons in outer space in any other manner.”

Other options include hiding within a population center, becoming the ruler of a sovereign nation or, as a variant of the high-seas option, building a hidden under-water base.

Is Batman a State Actor?

In Batman’s case, Commissioner Gordon is certainly a person for whom the State is responsible, and Batman often acts together with Gordon and obtains significant aid from Gordon in the form of information and evidence. Batman’s conduct is also otherwise chargeable to the State because the Gotham Police Department has worked with Batman on numerous occasions (and thus knows his methods) and operates the Bat Signal, expressly invoking Batman’s assistance in a traditionally public function. This suggests state action under the public function theory: “when private individuals or groups are endowed by the State with powers or functions governmental in nature, they become agencies or instrumentalities of the State and subject to its constitutional limitations.” Evans v. Newton, 382 U.S. 296, 299 (1966).

In the real world, this would cause significant problems for Batman and Gotham. Batman’s rough and tumble style would lead to a rash of Section 1983 claims for damages and probably also for an injunction against Batman’s future cooperation in police investigations. As discussed earlier, most evidence that Batman collects would be inadmissible, and police use of that evidence might bar the use of additional evidence collected during a subsequent police investigation.

Now, clearly none of this is the case, so there are three possibilities. Either all of the criminals in Gotham have incompetent attorneys, the state action doctrine in the DC universe is weaker than it is in the real world, or Gordon has actually managed to keep his reliance on Batman a secret. I’m going to opt for the second explanation. Superheroes like Batman are simply too effective for a court to shackle them with the Constitutional limitations of the state, especially with supervillains running around. Perhaps the DC universe courts have developed a public emergency or necessity exception to the state action doctrine whereby private individuals pressed into public service in an emergency are not held to the same standards as ordinary state actors.