The 74-year-old Italian premier was ordered Tuesday to stand trial on charges he paid a 17-year-old Moroccan girl for sex, and then used his influence to cover it up - an offense that, if proven, could see him barred permanently from public office.
Berlusconi has called the allegations "groundless" and dismissed the case as a "farce," accusing prosecutors of seeking to oust him from power. He did not comment Tuesday, skipping a news conference in Sicily and meeting with his lawyer in Rome.
Unlike Berlusconi's many past legal problems involving business-related charges concerning his Mediaset empire, this time he faces allegations of personal misconduct while serving as the head of government. The trial is set to begin April 6 before a panel of three female judges.
Prosecutors have already relayed more than 700-pages of wiretap conversations describing raucous behavior that would draw censure at most fraternity houses: sex-fueled parties attended by scantily clad women, sometimes dressed as nurses or police officers.
The indictment alleges Berlusconi paid for sex with the Moroccan girl, nicknamed Ruby, then used his influence to get her out of police custody when she was detained in connection with an unrelated theft of $4,103 (euro3,000). Prosecutors say Berlusconi called police the night of May 27-28, 2010, because he feared his relationship with the teen would be revealed.
So far Italians have been forgiving, with Berlusconi's popularity damaged by the scandal but not demolished. However, having such details aired in a courtroom and not just on newspaper pages could change the tide against Berlusconi, experts warn.
"If you start to hear something (that) is really embarrassing and difficult to handle, I think that could hurt the image of Berlusconi and his position as prime minister," said Franco Pavoncello, a political analyst at John Cabot University in Rome.
Judge Cristina Di Censo handed down the indictment Tuesday with a terse statement that showed she believes there is sufficient evidence to subject Berlusconi to an immediate trial, as prosecutors requested. The speeded-up procedure, which is ordered in cases of overwhelming evidence, skips a preliminary hearing that alone can take nearly a year.
The child prostitution charge carries a possible prison term of six months to three years. However, the abuse of influence charge is even more dangerous: It carries a sentence of four to 12 years, and if Berlusconi is sentenced to more than five, he would be barred from ever again holding public office.
Both Berlusconi and the now 18-year-old Moroccan nightclub dancer deny having had sex together. Ruby, in a TV interview on a Mediaset channel, said Berlusconi gave her $9,000 (euro7,000) the evening they met, and later jewelry.
The trial will follow the resumption of three other criminal cases involving Berlusconi's business dealings, creating both a legal morass for the premier, and a judicial juggling act as panels seek to schedule hearings amid Berlusconi's commitments as head of government.
At the same time, a weakened Berlusconi will face the challenge of keeping unruly coalition partners happy, while attempting to repair the image of his country - badly damaged by his own scandal - on the international stage.
The trial itself will take months, if not years, given the difficulty of scheduling court appearances. While defendants are not required to attend trials in Italy, Berlusconi's defense has often invoked his willingness to do so. Still, he has rarely showed up in court.
Berlusconi's supporters had pushed for jurisdiction to be transferred to the Tribunal of Ministers, which deals with offenses committed by public officials in the execution of their duties. They argued that Berlusconi intervened with the Milan police because he believed Ruby was the niece of now ousted Egyptian President Hosni Mubarak and was trying to prevent a diplomatic incident.
Pierluigi Bersani, the leader of the opposition Democratic Party, called for Berlusconi's resignation, demanding early elections. "We don't want Italy to be drifting," Bersani said.
A decision to dissolve parliament and hold new elections rests with President Giorgio Napolitano. He expressed concerns over the bitter conflict between the premier and the judiciary when the two met over the weekend.
While Italian politics is very polarized, Italians on the whole so far have been tolerant of Berlusconi's antics and gaffes, from cavorting with attractive young women to commenting on Barack Obama's skin tone.
Still, there are signs of discontent: More than a million women took to the streets over the weekend to protest what they called the denigrating treatment of women.
Ruby's fame, in the meantime, has only grown: The buxom beauty is frequently photographed in low-cut, tight-fitting attire at night clubs and has appeared in a television commercial wearing only black lingerie.
Over the years, Berlusconi has unashamedly flouted his attraction to beautiful young women - even insulting the looks of middle-aged opposition leader Rosy Bindi.
When his estranged wife Veronica Lario announced she was divorcing Berlusconi in 2009, she cited his involvement with young women and promotion of starlets to lawmakers. She also issued a plea to his friends to help him, saying "My husband is sick."
It remains to be seen how the trial will affect Berlusconi's role as Italy's chief statesman.
A masterful politician and businessman, Berlusconi has proven himself a champion at repelling previous legal challenges, many of which have ended when the statute of limitations expired. He recently survived challenges in parliament, winning two back-to-back confidence votes in December, though just barely.
Berlusconi's trial on tax fraud relating to the 1999 purchase of TV rights resumes later this month, followed by another accusing him of paying a witness to lie in court. Another tax fraud case, pertaining to events in 2007, will continue with a preliminary hearing next month.
To survive to the end of his third stint in 2013, Berlusconi will now find himself more beholden than ever to the Northern League. The populist party and government ally recently threatened to bolt to press passage of new rules giving cities and towns more power of taxation, part of their push to chip away at central authority in favor of the regions.
In an irony, Interior Minister Roberto Maroni, of the Northern League, is listed as one of the offended parties in the indictment, because police under his direct command were pressured to release Ruby.
Rizzo reported from Rome.