JERUSALEM — With squared shoulders and a surgical mask, Israeli Prime Minister Benjamin Netanyahu sat alone on a courtroom bench Sunday as a three-judge panel heard arguments in the mostly procedural opening session of his long-awaited criminal trial.

The proceeding, which will ­examine charges that Israel’s ­longest-serving prime minister accepted bribes and committed fraud and breach of trust in office, has already brought about an ­unprecedented clash between ­Netanyahu and the country’s criminal justice system.

The trial, which was delayed two months by Israel’s coronavirus outbreak, threatens to further divide the branches of Israel’s democracy, in a nation already deeply polarized after three elections in less than a year.

Minutes before the trial, a combative Netanyahu, broadcasting live on his social media platforms, called the cases against him “ludicrous” and said the investigations were “tainted from Day One.”

He decried the process as a sinister attempt to remove him from office. He called for the trial, which could last as long as two years, to be televised so that the nation could “witness the truth.”

Netanyahu was surrounded by his most senior ministers, who had turned out in a show of support, and in the streets outside the courtroom, a large crowd chanted their admiration for “King Bibi.” Supporters said they would never stop fighting for him.

Israel has navigated high-profile corruption cases before. Most notably, former prime minister Ehud Olmert was convicted in 2014 of taking money from real estate developers when he was mayor of Jerusalem. But Olmert resigned as prime minister before being indicted, as have other top officials who faced accusations of wrongdoing.

Netanyahu’s refusal to step down puts the country in uncharted territory, with each of his actions as prime minister likely to be weighed in light of his trial.

“The idea of having a sitting prime minister on trial, this one we haven’t seen before,” said ­Hebrew University of Jerusalem law professor Yuval Shany, vice president of research at the Israel Democracy Institute. “It’s a very serious situation for the country.”

Netanyahu has condemned the three-year legal process that has led to his trial as a political “witch hunt” by deep-state functionaries. He has turned his ire on Attorney General Avichai Mandelblit, whom he appointed.

Through the national elections of April 2019, September 2019 and March 2020, Netanyahu and his Likud party allies waged a blistering campaign against investigators and prosecutors, accusing them of bias, hubris and blind hatred. One Likud minister referred to Mandelblit as an alleged criminal in a radio interview last week.

“The head of the executive [branch] is essentially heading a crusade against the law enforcement branch of the government,” Shany said. “The next target is probably going to be the judges.”

Netanyahu has tried and failed to gain a vote of immunity from parliament. After he reached a power-sharing deal last month with his former rival Benny Gantz, opponents asked Israel’s High Court of Justice to block Netanyahu from heading the government while under indictment. The court rejected their request.

The trial opened a week after Netanyahu was sworn in for his fifth term. He enters the dock still in power, but without the near-total command of government he enjoyed for more than a decade. Gantz, who is scheduled to rotate into the premier’s job in 18 months, controls half the cabinet portfolios, including the Justice Ministry, which is in charge of the corruption case.

Academics and good-government groups, including several that sued to prevent Netanyahu from staying in office during the trial, have decried the rhetorical combat as politically and culturally corrosive. Netanyahu’s supporters say it’s the prosecution that’s hurting democracy. They point out that he made a strong showing in the three elections, all of which were held as the media was awash with news of the investigation and indictments.

“We have this exceptional situation where Netanyahu has refused to resign and the electorate and the political system have more or less come to terms with the idea that we are going to have the trial while he is in office,” Shany said.

Netanyahu faces counts of bribery, breach of trust and fraud stemming from alleged misdeeds going back a decade. Here are the cases, by their numbers in the Israeli court system.

● Case 1000: The first set of charges centers on allegations that Netanyahu and his wife, Sara, received gifts of cigars and jewelry worth around $280,000 in exchange for ­political favors. Mandelblit recommended that Netanyahu be charged with fraud and breach of trust. Among the people who allegedly supplied the gifts are ­Israeli-born Hollywood-based producer Arnon Milchan, whose film credits include “Fight Club” and “Pretty Woman,” and Australian business executive James Packer, who was briefly engaged to singer Mariah Carey. Prosecutors allege that between 2011 and 2016, Netanyahu lobbied U.S. officials to issue a visa to Milchan on two occasions and asked the finance minister at the time, Yair Lapid, to extend income tax exemptions to benefit Milchan. Milchan and Packer have provided testimony and were not charged.

● Case 2000: Netanyahu is charged with fraud and breach of trust in an agreement he allegedly sought with Arnon Mozes, publisher of the Yedioth Ahronoth newspaper and the Ynet news website. Under the alleged deal, Netanyahu was to advance legislation to weaken one of Mozes’s competitors, the free daily newspaper Israel Hayom, backed by U.S. Republican megadonor and casino magnate Sheldon Adelson, in return for favorable coverage. Mozes has denied wrongdoing.

● Case 4000: In what might be the most damaging case, Netanyahu is charged with bribery and breach of trust, accused of easing business regulations for Shaul Elovitch, majority shareholder of Bezeq, the country’s largest telecommunications company, in exchange for favorable coverage of Netanyahu and his wife on the popular news website Walla, also owned by Elovitch. Elovitch and his wife are also defendants in the case. Israeli police have said they have evidence that from 2014 to 2017, while Netanyahu served as minister of communications as well as prime minister, he intervened with regulators to help Bezeq merge with another large Israeli communications company. In exchange, police alleged, Elovitch instructed journalists at Walla to provide favorable coverage of the prime minister and his wife. Journalists, including senior editors from the website, have spoken publicly about being ordered to change headlines and photographs and remove or add content to boost the prime minister’s image. The Elovitches have denied wrongdoing.

  • Case 1000: The first set of charges centers on allegations that Netanyahu and his wife, Sara, received gifts of cigars and jewelry worth around $280,000 in exchange for ­political favors. Mandelblit recommended that Netanyahu be charged with fraud and breach of trust. Among the people who allegedly supplied the gifts are ­Israeli-born Hollywood-based producer Arnon Milchan, whose film credits include “Fight Club” and “Pretty Woman,” and Australian business executive James Packer, who was briefly engaged to singer Mariah Carey. Prosecutors allege that between 2011 and 2016, Netanyahu lobbied U.S. officials to issue a visa to Milchan on two occasions and asked the finance minister at the time, Yair Lapid, to extend income tax exemptions to benefit Milchan. Milchan and Packer have provided testimony and were not charged.
  •  Case 2000: Netanyahu is charged with fraud and breach of trust in an agreement he allegedly sought with Arnon Mozes, publisher of the Yedioth Ahronoth newspaper and the Ynet news website. Under the alleged deal, Netanyahu was to advance legislation to weaken one of Mozes’s competitors, the free daily newspaper Israel Hayom, backed by Republican megadonor and casino magnate Sheldon Adelson, in return for favorable coverage. Mozes has denied wrongdoing.
  • Case 4000: In what might be the most damaging case, Netanyahu charged with bribery and breach of trust for allegedly easing business regulations for Shaul Elovitch, majority shareholder of Bezeq, the country’s largest telecommunications company, in exchange for favorable coverage of Netanyahu and his wife on the popular news website Walla, also owned by Elovitch. Elovitch and his wife are also defendants in the case. Israeli police have said they have evidence that from 2014 to 2017, while Netanyahu served as minister of communications as well as prime minister, he intervened with regulators to help Bezeq merge with another large Israeli communications company. In exchange, police alleged, Elovitch instructed journalists at Walla to provide favorable coverage of the prime minister and his wife. Journalists, including senior editors from the website, have spoken publicly about being ordered to change headlines and photographs and remove or add content to boost the prime minister’s image. The Elovitches have denied wrongdoing.

Three of Netanyahu’s former confidants — Shlomo Filber, former director general of the Communications Ministry; former media adviser Nir Hefetz; and Netanyahu’s former chief of staff Ari Harow — have all become prosecution witnesses and turned over evidence.