The U.S. Supreme Court ruled yesterday that a Tennessee death row inmate should get a new hearing based on new DNA evidence:

The Supreme Court ruled on Monday that new evidence about a long-ago murder in rural Tennessee, including DNA evidence, raised sufficient doubt about who committed the crime to merit a new hearing in federal court for a man who has spent 20 years on the state's death row.

Justice Anthony M. Kennedy, writing for the 5-to-3 majority, called it "the rare case," and it was the first in which the Supreme Court has factored the result of modern DNA testing into the equation in re-examining a death sentence.

In another case, the Supreme Court ruled that a Florida death row inmate can proceed with a civil rights challenge:

The Supreme Court gave the green light for a Florida death row inmate to challenge that state's lethal-injection procedures through a federal civil rights lawsuit, in a unanimous ruling that underscored the pivotal role of Justice Anthony M. Kennedy in the court's death-penalty jurisprudence.

Clarence E. Hill, convicted in 1982 of murdering a police officer, did not claim that lethal injection, in and of itself, is cruel and unusual punishment. Instead, he asserted that Florida's method of executing inmates -- which, like that of most other states, employs three chemicals in sequence -- could subject him to excruciating but undetected pain, in violation of his civil rights.

According to the article, the ruling does not settle the issue of "whether, and under what circumstances, inmates generally can use civil rights law to challenge states' methods of execution."

In a related case less than a month ago, the Supreme Court refused to hear the case of another Tennessee death row inmate who appealed on the grounds that lethal injection is cruel and unusual punishment, a violation of the Eight Amendment.

Which begs the question: what is the humane and usual method for a state to kill someone? The Supreme Court apparently doesn't want to answer that one. But the ruling on new DNA evidence appears to be at least a step in the right direction.