I am very much opposed to the Death Penalty on the grounds that not only is it extremely unethical and unreliable on the grounds that there is always a risk of getting the wrong person but it's not even an effective punishment in the long run.
Even putting aside DNA and the massive improvements we've seen in forensics, how much more effective do you get than not having someone around? No chance of re-offending there!
The thing about execution, once the guy's dead it's not exactly possible to resurrect him, is it? Furthermore, there is always going to be the risk of getting the wrong person, which on those grounds alone helps to make Capital Punishment an unacceptable method.
Yes but are you going to give him back all the years he wasted in prison? And what about all the people that wind up being murdered, horrendously beaten or otherwise dying there? Plus with new technologies the rate of error is again, nominal. We're not talking about fingerprints or things like that which are falling by the wayside (justifiably so).
But many, many, many of the convictions already on the books are without DNA evidence (which I agree is very good) and many of the cases being tried now are without them. Requiring DNA evidence is probably even more impractical; the backlog is already immense, but would become astronomical if every case being considered for the death penalty were added.