Back in 2005, Justice Kennedy authored the majority opinion in Roper v. Simmons, which held it is cruel and unusual punishment to execute a person for crimes committed as a juvenile. 

The Roper opinion was controversial--not so much for its outcome as for its "internationalist" reasoning.  Kennedy, for a 5-4 majority, famously wrote:

"It is proper that we acknowledge the overwhelming weight of international opinion against the juvenile death penalty.... The opinion of the world community, while not controlling our outcome, does provide respected and significant confirmation for our own conclusions."

The response from the right was swift and severe.  Republicans on the Hill talked openly of impeaching Kennedy.  Tom DeLay, then House Majority Leader, blustered on conservative radio:  "We've got Justice Kennedy writing decisions based upon international law--not the Constitution of the United States. That's just outrageous." 

Fast forward three years... 

This term, in Kennedy v. Louisiana, the Court again focused its attentions on the intersection of the Eighth Amendment and capital punishment.  The petitioner in the Kennedy case, a convicted child rapist, argued that it's cruel and unusual punishment to impose the death penalty for the commission of a non-homicide offense.  Taking cues from Justice Kennedy's reasoning in Roper, amici briefs set forth authority indicating a "global consensus" on sentencing for child rape. 

Yesterday the Court issued it opinions in the Kennedy case.  Overturning petitioner's death sentence, a 5-justice majority concluded that capital punishment for non-homicide offenses against individuals is indeed cruel and unusual. 

Just like in Roper, Justice Kennedy authored the majority opinion. 

Just like in Roper, Kennedy wrote on behalf of Justices Stevens, Souter, Ginsburg, and Breyer. 

But this time around, Kennedy made no reference to foreign law or a global consensus.      

Draw your own conclusions.