One recent controversy involving the constitution is the right to referendum which is mentioned in the Constitution. The constitution states that "The exercise of the rights of initiative and referendum shall be prescribed by law", but legislation prescribing the practices had been blocked by the pan-blue coalition largely out of suspicions that proponents of a referendum law would be used to overturn the ROC Constitution and provide a means to declare Taiwan independence. A referendum law was passed on November 27, 2003 and signed by President Chen Shui-bian on 31 December 2003, but the law sets high standards for referendums such as the requirement that they can only be called by the President in times of imminent attack.