Is jury duty a trolley type problem? What should one do?

Once again I've been called in for Jury Duty.

It's nearly a priori that they won't impanel me for death penalty or war-on-drugs type cases, since I'm up front about exercising my right to jury nullify in the case of unjust laws or state sanctioned murder.*

But I have no idea what to do with respect to someone who has both broken a just law and who should not be on the streets.

How can anyone in good conscience send another human being to an American prison?

But as a juror the only choice they give you is sending the person to prison or releasing them. And many people are too predatory to be allowed to operate in normal society. 

I've got two weeks until I have to go in. Any advice about from people agree with me that this is a genuine dilemma** and/or have some experience negotiating the system would be greatly appreciated.

[*From the other time I got called in, if you tell the lawyers, judges, etc. that your opposition is religiously based, they will leave you alone, but if you try to engage them in rational dispute, they'll get pretty angry and the prosecutor will probably mislead you about what constitutes jury misconduct.

**If you don't see it as a dilemma, you could do much worse than spending this Sunday evening listening to the sermon from which the above video is excerpted. Go here and click on the little green box with the white arrow in it. I hate to contribute to what Roger Ailes' yes-people call the wussification of America, but I do prefer this kind of thing to watching people give one another brain injuries.]