The Limits of Self-Defense

Although I am an advocate of preemptive warfare (see here, for example), I am firmly opposed to the notion of preemptive criminalization, as in the movie Minority Report. What I didn't know is that preemptive criminalization (like involuntary euthanasia) has already arrived in Europe, according to Stephen Sedley, writing in the London Review of Books:

What is the rationale of objection to a comprehensive national DNA database?....

There remains the concern about possible abuse, that the police might in future use the data not merely for detection but for personality profiling – especially since one of the purposes already sanctioned by law is crime prevention. I think this concern is real. A number of states – and there are indications that England and Wales may join them – have begun to allow the indefinite detention of sexual offenders on the basis of predicted behaviour.

Frightening, especially because it might be picked up as a "liberal" cause in the United States.