Well Damian beat me to it masterfully again.
I shall therefore assume that gl has his/her answer. I also assume he/she should start to understand the distinction between the penalty punishing a crime and the way justice (infallible or not) is served. These are two separate things, the later being more than often (say, in China) nothing but a sham to justify ultimate or disproportionated penalties to punish opinion crimes (that is to say imaginary crimes)
As Damian put it, it's about proportionality, not justice in the sense of a set of laws enforced by a judicial system - and so I guess it's time to quote Jefferson in full now: "Rightful liberty is unobstructed action according to our will within limits drawn around us by the equal rights of others. I do not add 'within the limits of the law' because law is often but the tyrant's will, and always so when it violates the rights of the individual."
And you still have to answer Damian's question by the way, to which I would add: how come the anti-death penalty mob is so concerned about it taking place in the USA under the conditions exposed here before, but just don't give a flying f* about places such as China (20.000 executions since 1990 after "grossly unfair and summary trials") North Korea, or a large chunk of Africa?