The October issue of the Foreign Service Journal considers the ways U.S. support for capital punishment affects, and is affected by, international opinion, in "World Opinion Weighs In: The Death Penalty & U.S. Diplomacy."
Most of the articles aren't available on AFSA web site, but they might be worth hunting down .
"American Diplomacy and the Death Penalty"
By Harold Hongju Koh and Thomas R. Pickering
"The Death Penalty, America, and the World"
By Paul Rosenzweig
"International Influence on the Death Penalty in the United States"
By Richard C. Dieter
"The Myth of the Cowboy"
By Greg Kane
"A Decent Respect to the Opinions of Mankind"
By Paul P. Blackburn