WASHINGTON – U.S. Supreme Court arguments over the constitutional power to make and implement treaties took a dramatic turn Tuesday when Solicitor General Donald Verrilli Jr. warned justices that a ruling interpreting the meaning of a chemical weapons treaty would be “terribly unfortunate” and could disrupt “very sensitive negotiations” underway with Syria and other nations.

Verrilli’s statement seemed to irritate the court, which does not usually like to be told that it should steer clear of an important issue in a pending case. Justice Stephen Breyer, usually an ally of the Obama administration, told Verrilli with annoyance that if national security was at stake in the dispute, “the State Department better file a brief” saying so. “Is that what you are telling me,” Breyer added incredulously, “that if I write the opinion that I think the law requires me to write, that I am somehow hurting the national security interest of the United States?”