My criticism of the US is that you allow these arseholes to keep appealing. If you have absolute proof of guilt AND the offence is sufficiently serious, sentence should not be appealable.
A few years ago me and some friends actually took the time to design a new trial/appeals process with the idea of actually providing a solution to the long appeals process but still allow the chance to find errors, I will offer a very short outline of our idea:
All capital crimes to be video recorded to include all sidebars and meetings in Judges chambers.
Once a verdict of guilty is found, the Government provides the defense a copy of the tapes within 30 days.
The defense then has 90 days to create a complete list of "ALL" appeals. They use video tags to provide context and content. If they believe 40 things were done wrong, then all 40 must be included on that list, no changes or additions are allowed after that 90 days.
The list and video is passed by the prosecuters office who has 60 days to provide rebuttal of the appeals, again point by point in writing.
The final product of both is then sent to a 3 Judge (many of these can be formed) appeals court that reviews each appeal, point by point going down the list. NO LAWYERS talking to the Judges, it is law, no need for theatrics. If all of the appeals are denied, the process is over. They can then apply to the federal/suppreme court but everything is done on the State level.
There are actually pages of details we outlined but I severely simplified the idea for the sake of posting as short as possible here.
In my opinion, the death penalty is not very effective as a deterrent for two reasons, it takes too long to kill the scumbag after the crime so there is no direct crime/punnishment connection, and second, even when it is done, it is too well hidden, they should at the least to pay-per-view and public hangings would be even better.