Like most everyone here, I'm against the death penalty.
Now, if I weren't against the death penalty, I'd want stricter enforcement of the standards that are, theoretically, built into the law. That is, a person must be competent to stand trial, and they must have understood what they did. And if they didn't understand what they did, I'd want to make sure they were put into a treatment facility with some very involved procedures for getting out again, to avoid releasing people who are still a danger to themselves and others.
As it is, I don't think courts are doing due diligence in protecting either the mentally ill from undue punishment or the public from the dangerously insane.