JERUSALEM (AP) — Thousands of Israeli doctors walked out of work, labour leaders threatened a general strike and senior justices rushed home from a trip abroad Tuesday, a day after the government approved a law weakening the country’s supreme court that critics say will erode the system of checks and balances.

Four leading Israeli newspapers covered their front pages in black ink — an ominous image paid for by an alliance of high-tech companies. The only words on the pages were in a line at the bottom: “A black day for Israeli democracy.”

Monday’s vote — on the first of a series of measures that make up Prime Minister Benjamin Netanyahu’s divisive judicial overhaul — reverberated across the country. It came despite seven months of fierce popular resistance, Netanyahu’s promises of an eventual compromise and a rare warning against the overhaul from Israel’s closest ally, the United States.

The bill was unanimously passed by the governing coalition, which includes ultra-nationalist and ultra-religious parties, after the opposition stormed out of the hall shouting “Shame!” But opponents say they are not done fighting it: Civil rights groups submitted petitions to the Supreme Court, calling for the new law to be overturned, and protests roiled the country’s streets overnight.

Hundreds of thousands of people fanned out in Tel Aviv, burning tires, setting off fireworks and waving national flags. In central Jerusalem, police mounted on horses unleashed water cannons and a foul-smelling spray at protesters, arresting nearly 40 people. At least 10 officers were assaulted and injured, they said.

Israel is now hurtling into uncharted territory against the specter of further social and political unrest. Thousands of officers in the military reserves have announced they’ll no longer turn up for voluntary service — a blow that could undermine the country’s operational readiness. High-tech business leaders are considering relocation.

The overhaul also threatens to strain ties with the Biden administration, jeopardise the country’s new alliances with Arab states and deepen Israel’s conflict with the Palestinians, analysts say.

“I think this country is going to either split into two countries or be finished altogether,” said Yossi Nissimov, a protester in a tent city set up by demonstrators outside of the Knesset, or parliament, in Jerusalem.

The vote on the law came just hours after Netanyahu was released from the hospital, where he had a pacemaker implanted, adding another dizzying twist to an already dramatic series of events.

The Israeli Medical Association, which represents nearly all of the country’s doctors, announced they would strike en masse Tuesday across the country, with only emergencies and critical care in operation.