A lawyer writes:
As a basic rule, a prosecutor's ideal juror is a conservative white person without a college degree. They're generally pro-prosecution, but unlike conservative, educated white people, they're not smart enough to sniff out a bogus prosecution. Liberal, educated white people can go either way -- it depends a lot on the case. On some crimes, they're a prosecutor's nightmare, but on, say, DWI, they're generally favorable. And, if you're talking about liberal, educated white women, they can be a defense attorney's nightmare in something like the Scott Peterson case (or a rape case.)
A defense attorney's ideal juror is poor, uneducated, and a minority -- i.e., somebody who will probably sympathize with the defendant. Also, while uneducated white people aren't smart enough to sniff out the b.s. that a prosecutor feeds them, uneducated minorities tend to go the same way for the defense -- they'll believe almost any alternative theory that the defense attorney feeds them, no matter how bogus it might seem to a smarter person..