Prisons are an outsized business in California, and these days Californians have an outsized monument to their fear of something prisons cannot contain: sex crimes. At Coalinga State Hospital sex offenders who have served prison terms are serving more time, having been involuntarily committed as “sexually violent predators.” Californians appear determined to fill the place and then some, as a referendum last November expanded the commitment law to make virtually every sex offender in the prison system eligible for lifetime detention. And so the numbers at Coalinga, now about 670, will never stop growing.

Coalinga is preventive detention in perfect form. The inmates are confined for what they think, or what they might do if released or, more precisely, what a psychologist guesses they might do. If that seems unconstitutional in a 1970s kind of way, the courts are largely unmoved. And if people are locked up for years before a court asks too many questions, it is because of what some lawyers call “the pedophile exception to the due-process clause.”

Maybe it would be surprising if America, now accustomed to the terrorist exception to the Constitution, was not warm to a pedophile exception. But legal scholars and psychiatric experts have almost nothing good to say about using the mental health system to institutionalize offenders. The idea has proven an especially bad one in California, whose mental hospital system is under federal monitoring because of widespread civil rights violations. The costs of running Coalinga, already galloping, are compounded by the costs of processing thousands more offenders; under the new Jessica’s Law, the number referred for evaluation has risen from fifty to about 750 each month.

In its enthusiasm for preventive detention, California, as is its tendency, is like all America–only more so. The word “predator,” not so long ago a mere metaphor, has come to encompass flashers and peeping toms, and locking up the whole lot of them has become a legislative reflex across the country. Eric Janus, president and dean of the William Mitchell College of Law in St. Paul and the author of Failure to Protect, about the civil commitment laws, refers to a “third wave” in the last couple of years.

Around 1990 a handful of states rewrote their mental health laws to reel in sex offenders–most of whom were not mentally ill by any definition–as their prison terms expired. In the mid-’90s, especially after the Supreme Court upheld Kansas’s Sexually Violent Predator Act, a dozen others followed suit. The panic flared again in 2006 and ’07: New Hampshire and New York enacted commitment laws, and a change in Virginia’s law quickly tripled its detainee population. Congress approved the civil commitment of sex offenders in federal prisons, including the growing percentage who land there on pornography charges.

“I was thinking probably it was going to go away, with states scared off by the financial burden,” Janus said. “But what with New York jumping in, that’s a bellwether state in some ways. It would be a little surprising if it didn’t spread further.”

At this point legislators need not worry about the courts. The laws may rely on a web of legal fictions–that the inmates are psychiatric patients, that their detention is not punitive, that actuarial tests can predict their behavior–but they are Supreme Court-approved fictions. In the 1997 decision Kansas v. Hendricks Justice Clarence Thomas wrote that the offenders were not being punished and that their rights to personal liberty were outweighed by the demands of public safety.

The pronouncement that the commitments are civil rather than criminal makes it possible to dispense with a lot of fact-finding. Civil commitment does not require the constitutional protections afforded defendants accused of, say, kiting checks or stealing cars. The process can skirt concerns like cross-examining accusers or airing exculpatory evidence. It can rely on psychiatrists who may base their opinions on any evidence at all, including accounts of long-ago offenses that were never investigated or heard by a court. Some states do not allow juries or open hearings.

The California law provides for a trial, but not a speedy one. Defense lawyers detect no sense of urgency on the state’s part, and a spokesman for the Coalinga residents, Niles Carr, says about half do not have lawyers assigned to them. Carr himself is temporarily committed; he’s been awaiting trial for nine years.

The federal commitment law took a hit in September when a federal district judge held that Congress did not have the authority to confine people leaving federal prisons–although the states could do it. Three of the five plaintiffs, who were certified as “sexually dangerous persons” and held at the prison in Butner, North Carolina, had served time for receiving or possessing child pornography. There’s no telling from the decision whether any of the pornography defendants poses a danger to anyone beyond his computer screen. But the case invites questions about whether prosecutors are in fact capturing the people they so often call “the worst of the worst.”

The worst of the worst are, in fact, being imprisoned for longer and longer terms. Among the more than 4,000 men who have been committed under these laws in twenty states are many indisputably violent criminals–though few murderers. There are men who assaulted women. There are flashers and voyeurs, legions of child molesters whose crimes did not involve force or penetration and gay men who had sex with teenagers. (In some states, soliciting a minor is a qualifying offense.)

Treatment may or may not be a fiction. Most Coalinga inmates do not participate in treatment, in part because therapists’ reports can be used against them in court. Those who do follow the program, in California as elsewhere, almost never satisfy their jailers. More than 200 men identified as sexually violent predators by the state’s Mental Health Department have been released by the courts, usually without any treatment, but, according to spokeswoman Nancy Kincaid, the department has never recommended release. When it tracked ninety-three of those released over a six-year period, it found that six had been arrested for new sex crimes.

As for the pileup of new candidates awaiting evaluation, Kincaid said very few would be committed. But Coalinga has plenty of room. It was built two years ago, at a cost of $388 million, to house 1,500 men. In California, that’s barely a start.