It is a matter of dismay that the Supreme Court of one of the world's greatest democracies should still find itself comfortable with ruling that the use of lethal injection on someone doesn't constitute cruel and unusual punishment. It's high time that that august body re-examined its own legal concepts in light of the meanings of words available to ordinary people, which I take it the members of the Supreme Court also are, their membership of it notwithstanding.
There was a time, I suppose, when relative to its occurrence in other countries, killing a person for punishment wasn't all that unusual. But it has become increasingly so. Relative, in any case, to frequencies within ordinary law-governed life, punishment of anyone by killing them is certainly most unusual.
As for the cruelty of it, how can any civilized person look squarely at the procedure of doing someone to death before their time by administering an injection, and fail to see any cruelty in it? Have the Justices on the Court stopped to think about a person's last days and moments before an event like this? Note that nothing I say here is enough to establish that capital punishment can't ever be justified - though I think it can't. But if cruel and unusual punishment is unconstitutional in the US, then execution by lethal injection should be so, and execution in general.