The High Court of Justice on Thursday ordered the government to provide within 21 days a legal justification for the power-sharing agreement between the Likud and Blue and White parties.
The move, seen as another blow to a coalition already fraught with tensions and challenges, was slammed by Likud officials, including Knesset Speaker Yariv Levin, who said it was politically motivated.
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The court's move followed a petition filed by the Movement for Quality of Government, Meretz and other organizations against articles in the unity government deal naming an "alternate" prime minister and seeking to amend Basic Law: The Government accordingly.
In the absence of a constitution, the Basic Laws of Israel are meant to regulate key issues pertaining to the formation and role of principal state institutions, the relations between various state authorities and the decision-making process of the governing bodies. The petition questioned the need to change the benchmark legislation for the sake of a political deal, claiming it constituted an abuse of power.
The Movement for Quality Government welcomed the court's ruling, saying, "It must not come to pass that Israel's ruling regime changes to accommodate a defendant in three indictments, who is trying to escape the threat of justice."
This refers to Prime Minister Benjamin Netanyahu, who is currently on trial for multiple corruption indictments including bribery, fraud and breach of public trust. Netanyahu vehemently denies all allegations of wrongdoing.
According to petitioners, the power-sharing agreement creates two different governments, each headed by a different prime minister, which in turn, compromises parliamentary democracy in Israel.
The unity deal between Likud and Blue and White includes a rotation agreement, by which Netanyahu will serve as prime minister until November 2021, at which time Gantz is slated to assume office.
The deal, which sought to end a prolonged political crisis that included three back-to-back elections, required the Israeli parliament to amend Basic Law: The Government, which the court is now challenging.
"The High Court of Justice, in its outrageous decision, is laying the groundwork for crossing the red line of intervening in Basic Laws," Levin said. "They do not have the authority to intervene in a way that is contrary to the most basic principles of democracy and is therefore fundamentally void."
Coalition Chairman MK Miki Zohar said, "It is not the court's place to intervene in coalition agreements."
Likud MK Osnat Mark, a member of the Judicial Nominations Committee, slammed the High Court for trying to "shut down the country. There is a government in place but for some reason, it [the court] sees itself as the sovereign."
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The opposition seemed split on the matter.
Opposition Leader Yair Lapid (Yesh Atid), said, "Let me save you 21 days - there's no need for an alternate prime minister."
Yamina MK former Justice Minister Ayelet Shaked said that while "there was never any need to amend the Basic Law, it is not the court's place to intervene in the Knesset's decisions on these matters."
Yamina MK Ofir Sofer warned that "the possibility that the High Court of Justice would repeal an amendment passed by the Knesset is dangerous."
Meretz leader Nitzan Horowitz welcomed the High Court's decision, saying, "Even the court understands that changing constitutional legislation to support a warped political deal is wrong. The deal struck between Likud and Blue and White is morally and legally wrong. It is tantamount to stealing the elections and trying to change the rules of the political game to match the result."
i24NEWS contributed to this report.