JERUSALEM — A pair of Israeli rights groups on Wednesday asked the country’s Supreme Court to overturn a new law legalizing dozens of settler outposts in the West Bank, opening what is expected to be a lengthy legal battle over the contentious legislation.

The legal challenges added new uncertainty to the law, which has drawn fierce international condemnations and been questioned by Israel’s own attorney general.

The law, backed by Prime Minister Benjamin Netanyahu’s nationalist coalition, retroactively legalized thousands of homes found to have been built on private Palestinian land. While its backers claim these homes were built “in good faith,” critics say the law amounts to legalized land theft.

In the first lawsuit against the measure, the Arab rights group Adalah and the Jerusalem Legal Aid and Human Rights Center asked the high court to block implementation of the law. It was the first in what is expected to be a series of legal challenges.

“This sweeping and dangerous law permits the expropriation of vast tracts of private Palestinian land, giving absolute preference to the political interests of Israel,” said Suhad Bishara, an attorney for Adalah.

She said the court gave Israel 30 days to respond. She added that Adalah had requested the court freeze the law’s implementation until its final ruling.

In the meantime, the state can begin implementing the law. Experts say the legalization process will take years as authorities identify properties, confiscate lands and work out compensation with the original Palestinian owners.

The West Bank is home to some 120 settlements recognized as legal by Israel, as well as about 100 unauthorized outposts that the government has tacitly accepted.

The new law sets out a process to legalize about half of those outposts, as well as about 3,000 additional homes built illegally in recognized settlements. Palestinian landowners can receive financial compensation or alternative land.

The Palestinians seek the West Bank and east Jerusalem, captured by Israel in the 1967 Mideast war, as parts of a future independent state.

Most of the international community considers all Israeli settlements illegal and counterproductive to peace by gobbling up the territory sought by the Palestinians. Some 600,000 Israelis now live in the two areas.

After years of conflict with President Obama over settlements, Netanyahu’s hard-line government has grown emboldened by the election of Donald Trump. The new president has signaled he will take a much softer approach to the settlements.

Since Trump took office, Israel has approved plans to build more than 6,000 new homes in the West Bank and east Jerusalem.

Peace Now, an anti-settlement watchdog group, said that one of the newly approved projects is connected to a Jewish seminary in the Beit El settlement. Trump’s proposed ambassador to Israel, David Friedman, has been a top fund-raiser for the same seminary.

The Israeli building announcements, coupled with passage of the new law late Monday, have drawn condemnations from many of Israel’s closest allies. The European Union, as well as Britain, Germany and France, have all spoken out against the law. The U.N. has also condemned the measure.

Trump, however, has remained largely silent. Last week, the White House said that new settlement construction “may not be helpful” to promoting peace. White House spokesman Sean Spicer has said the new Israeli law will be discussed next week when Netanyahu meets Trump in Washington.

Trump’s departure from the policies of previous Republican and Democratic administrations has alarmed the Palestinians.

“We do not know what is going on between Netanyahu and President Trump’s administration, but at the end of the day we say that whoever wants to achieve a just and historical peace in the region between the Israelis and the Palestinians cannot be silent on settlement activity,” Palestinian official Saeb Erekat said on Palestinian radio. “It’s time for President Trump to tell Netanyahu, ‘Enough.”‘

The new law, meanwhile, faces an unclear future. Israel’s attorney general, Avichai Mandelblit, has said he will not defend it in court.

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