Somali Pirate under a flag of truce?

[Excaliber]

Ron Kuby, a New York-based civil rights lawyer, said... (about the pirate captured and now enroute to NY for prosecution),

"I think in this particular case, there's a grave question as to whether America was in violation of principles of truce in warfare on the high seas," said Kuby. "This man seemed to come onto the Bainbridge under a flag of truce to negotiate. He was then captured. There is a question whether he is lawfully in American custody..."

An interesting legal argument. The point Kuby makes here sounds more like something that would apply during times of war with enemy combatants/negotiators, rather than law breaking thug's and kidnappers with NO declared war in effect.

Anyone have any insight as to what Maritime law(s), or "principles of truce" that apply to this case?