TEL AVIV, Israel — Prominent U.S. lawyer Alan Dershowitz, long a staunch defender of Israel’s policies on the international stage, said Sunday he cannot defend sweeping judicial reforms planned by Israel’s new government.

The proposals call for an overhaul aimed at curbing the powers of the judiciary, including by allowing lawmakers to pass laws that the Supreme Court has struck down. The reforms would give politicians more power over how judges are chosen and limit the independence of government legal advisers, among other steps.

The legal reforms were essential to solidifying the current coalition government, headed by Israeli Prime Minister Benjamin Netanyahu and made up of conservative ultranationalist and ultra-Orthodox parties who seek to advance their agenda through less judicial oversight.

Dershowitz said the reforms pose a threat to civil liberties and minority rights in Israel.

“If I were in Israel I would be joining the protests,” Dershowitz told Israeli Army Radio, referring to a protest in Tel Aviv on Saturday against the reforms that drew thousands.

“It will make it much more difficult for people like me who try to defend Israel in the international court of public opinion to defend them effectively,” he said. “It would be a tragedy to see the Supreme Court weakened.”

It was unusual to hear Dershowitz, who has written bestselling books supporting Israeli policies and is close to Netanyahu, so forcefully opposing the proposed reforms. Dershowitz said he had informed Netanyahu recently of his “very strong, negative views” of the reforms, saying they would also expose Israel to legal challenges by global bodies such as the International Criminal Court.

The reforms could also help Netanyahu, who is on trial for corruption, evade a conviction or see his trial disappear entirely. Dershowitz said he believed Netanyahu agreed to the reforms not to save himself from a conviction but rather to appease the partners of his new governing coalition.

Critics accuse the government of declaring war against the legal system, saying the plan will upend Israel’s system of checks and balances and undermine its democratic institutions by giving absolute power to the most right-wing coalition in the country’s history.

The government says the plan strikes the right balance between the executive and judicial branches while streamlining governance and legislation.