subject of Arresting the White Death[1] was civil confinement for treatment of tuberculosis, a particularly burdensome form of quarantine; the paper's primary purpose was to understand how such quarantine could be morally justified. Because of the obvious analogy between quarantine and I also discussed demolishing a defense of detention relying on that analogy. So, of course I was surprised to find Corrado criticizing my defense of detention - more surprised when I realized I had a defense to criticize. How did I end up defending detention? What does the answer to that question tell us about Corrado's argument and mine? In the course of trying to answer these questions, I shall argue: (a) that Corrado has misunderstood my defense of detention; (b) that his misunderstanding makes most of his criticism beside the point; and (c) that my defense, though philosophically interesting, leaves most of the important questions open. Some Basic Distinctions Almost two decades ago, Ferdinand Schoeman published a paper arguing that detention of potential criminals to prevent crime is morally no more problematic than quarantining the contagious to protect public health. Though much reprinted since, the paper has received little criticism. No doubt the practical ignored it because Schoeman did not address their problems. His target was philosophical, the moral criticism that detention violated a person's right to punishment. Schoeman's argument seemed to show that the right to punishment, if it existed at all, did not count for much. Since the right to punishment, then associated with Herbert Morris, underwrote much of the revival of retributivism, we would expect Schoeman's argument to have provoked philosophical retributivists. It did not. Why not? My guess is that they found it paradoxical enough to consign to that category of low-priority puzzle of which Anselm's Ontological Argument is the exemplar: hard to prove invalid for interesting, if technical, reasons, but certain to be proved invalid sooner or later. The White Death could not do the same because Schoeman's argument, insofar as it did not quiet doubts about the moral justification of raised doubts about the moral justification of quarantine. By preventive detention, I mean holding a person (a rational agent) against his will to prevent him from committing a crime. Presupposing that the detainee is rational, detention differs substantially from commitment for mental illness or incompetency (which presupposes that the committed is not fully rational). Preventive detention may be civil or criminal. Civil detention uses procedures like those of an ordinary incompetency hearing. Criminal detention uses the procedures of the criminal law. While the place of civil detention may be different from that of criminal, it need not be. Even criminal detention is (as such) not punishment. Like quarantine is an extensive interference with the liberty of some rational agents to protect others.[2] Quarantine differs from detention in what it is supposed to protect others from. Preventive detention is supposed to protect others from the serious crimes that the detainee would otherwise commit; quarantine, to protect others from serious disease the quarantined would otherwise spread. Quarantine also differs from detention in apparent moral status. While detention has always seemed morally problematic, quarantine generally has not. What Schoeman argued was that because quarantine and detention differ in no morally significant way (except apparent moral status), detention is morally no more problematic than quarantine. apparent difference in moral status is only that, an apparent difference. …