The legislation, passed in July, eliminated the Supreme Court’s reasonableness clause, a power given to the court to overturn government rulings deemed unreasonable.
The clause was one of several tools held by the judiciary to provide checks on the other branches of government.
The controversial legislation had led to mass protests from January 2023 to October 2023.
Eight of 15 Supreme Court justices ruled in favour of nullifying the law, according to the court.
The Supreme Court decision comes after an Israeli news outlet, Channel 12, reported on a leaked draft copy of the court’s decision to nullify the law.
The leak caused the court to expedite its release of the decision, which originally had a deadline of 12 January, according to Haaretz.
Since the outbreak of the war on Gaza, several judges asked two of the Supreme Court justices to consider delaying the ruling’s publication. However, according to a report by the daily, that request was dismissed.
A source at the court told the Israeli newspaper last Thursday that the leak of the decision went against the Supreme Court’s ethos, damaging its honour and the relations between the justices.
Netanyahu’s political party, Likud, called the court’s decision unfortunate and said it opposed “the will of the people for unity, especially during wartime”.
Israel’s Justice Minister Yariv Levin, and one of the chief proponents of the planned judicial overhaul, criticised the nation’s highest court for “taking all powers”.
Levin said “judges are taking into their hands all the powers, which in a democratic regime are divided in a balanced way between the three branches” of government.
“It takes away from millions of citizens their voice,” Levin added.
The law had been part of a package of bills proposed by Netanyahu’s government earlier this year, seeking to overhaul the judicial system in the country.
Netanyahu’s government, deemed the most far-right in Israel’s history, has made the judicial overhaul a priority since coming into office earlier this year.
Israel does not have a written constitution – only a set of roughly defined Basic Laws – and has a heavily centralised executive branch, with little separation from the legislative branch. So the Supreme Court is seen as the most effective check on government power.
Critics have claimed that the “reasonableness” assessment is too vague and subjective, and has given too much power to unelected officials.
Supporters say that its integration into Israeli law over the decades has prevented the country from sliding into authoritarianism.
The changes made by the law sparked consecutive months of protests inside and outside of Israel, with former Israeli officials and Israel’s staunchest ally, the United States, warning against the “divisive” judicial overhaul.
Netanyahu’s removal of the reasonableness standard had also sparked concerns from western allies, including US President Joe Biden urging Netanyahu and his government to roll back the changes, creating a tense moment between two close allies.
