US Guantanamo tribunal lacks basic law

"It's astonishing that the United States would try a case of historic importance with officials who are struggling to grasp basic legal concepts," said James Ross, senior legal advisor for Human Rights Watch, who observed the hearings.

"Real courts with real judges should be trying these complex cases, not tribunals started from scratch."

About 540 detainees have been held for two and a half years at a US navy base in Guantanamo, Cuba.