[Update: ScotusBlog flags for me that Stevens' opinion is formally a "statement," but I see that Breyer's is labeled a "dissent." Stevens basically uses the opinion as an example of a problem, while Breyer formally notes he would vote to hear the case. Stevens in effect provides a concurrence like in Baze v. Rees, where he states his opposition to the death penalty, but notes that he will follow current precedent that allows it.]
Now and again, a justice writes an opinion dissenting from the Court not hearing a case, generally to make known a subject matter they feel warrants examination. In the scheme of things, they might be glad that the matter was not heard, since the result might not to be to their liking. Not that justices are just results-orientated! Such opinions can have a personal flavor, since they need not be agreed upon by the Court as a whole, and specifically deal with issues that might not otherwise be particularly covered in that fashion. Such opinions are found on the Supreme Court website, but generally do not get much press. And, is not just a matter of the justice wishing to hear the case without the usual three other votes needed, which comes up somewhat more often.
Justice Stevens recently wrote opinions of this nature in two death sentence cases, both which received some support from at least one justice. First, with videos provided, he argued that the development of victim impact statements in capital cases has reached a state of development that some standards need to be decided upon to guide lower courts. Even if statements of victims during the penalty stage is legitimate, which he does not agree to, elaborate emotional laden videos might be a step too far. The second case involves the death penalty directly, particular those cases that have lingered for decades, a matter Justice Breyer also has addressed in this fashion. In this case, Justice Thomas concurred in the denial.
The basic concern is that there are cases that have lingered, with multiple last minute stays of execution, into a third decade. This wait, in itself, might be deemed cruel and unusual. Thomas argues that the litigant is to blame -- he is the one who brought up continual appeals, and did not agree to the "reasonable" (as Justice Breyer admits) judgment that he deserves the death penalty based on particularly heinous facts. You cannot have your cake and eat it too. All the same, if the delay is a result of the state violating his due process, why should he to be blamed for the length of the appeals process? We are not talking a few years here -- normal capital appeals generally can take the better part of a decade, if done quickly. We are talking decades.
Justice Thomas' opinon only tempers the arguments of Stevens and Breyers. Stevens raises the matter of the heinous nature of solitary confinement. Thomas is correct in saying that it is in some significant part a result of reasonable safety concerns. Without a death penalty, safety will warrant keeping some people in horrible conditions. But, the death sentence factors into the placement. Thomas discusses, in detail, the horrible nature of his crime. This counters -- up to a point -- Breyers detail that suggests possible mitigation. But, as with Scalia raising the point when Justice Blackmun said he will no longer tinker with the machinery of death, was the murderer's compatriot really so less heinous here to not warrant the death penalty?
The fact that even when the death penalty can be defended on some grounds, such as the horrible nature of the offense, that it still can be shown to be arbitrary underlines its problems. Thomas is correct to suggest no punishment can be error free. The problem is that there can be some point where error and other problems makes it unconstitutional.