Prime Minister Binyamin Netanyahu's abrupt need for surgery reinforced the need for Israel to have a law indicating who takes power in such circumstances, former Knesset speaker MK Reuven Rivlin said on Sunday.When Ariel Sharon was prime minister, he appointed Ehud Olmert as his vice prime minister, a title that granted him the automatic right to take over for Sharon when he was abroad or physically unable to perform his duties. Netanyahu has not given any of his ministers that title in this term or the previous one, in part because he wanted to avoid initiating a succession battle between politicians inside his Likud party.Because there is no vice prime minister, cabinet secretary Avichai Mandelblit had to conduct a poll of ministers by telephone late on Saturday night to approve the appointment of Defense Minister Moshe Ya’alon as acting prime minister during Netanyahu’s hernia surgery. When Netanyahu has gone abroad in this term, he has given the acting prime minister post to Ya’alon or International Relations Minister Yuval Steinitz, and when he went to Poland with Ya’alon and Steinitz, to Public Security Minister Yitzhak Aharonovich.Rivlin said prime ministers should be obligated to appoint a vice prime minister to avoid situations like Saturday night’s, when ministers had to be woken up to vote on a technical matter. He recommended passing a law to mandate such a change.“From a legislative point of view, we should decide who the acting prime minister is when the prime minister does not appoint one,” Rivlin said.It was Rivlin who persuaded Sharon to appoint as his vice prime minister Olmert, who had been Rivlin’s sworn political enemy for decades. Rivlin made the suggestion in order to solve a dispute inside the Likud at the time, not knowing that the move would lead to the coronation of his adversary.None of the current electoral reform proposals that are in the process of passing in the Knesset deal with the issue of succession. But previous Knessets tried unsuccessfully to pass bills that would clarify the issue.The Movement for Quality Government wrote Netanyahu two months ago urging him to appoint a vice prime minister.His office responded to the organization that he had no legal obligation to do so.