Brazilians are consumed with a number of momentous questions at the moment – including whether the President will resign or be impeached, and if so, who will replace her.

But beyond the minute-by-minute political tumult playing out in Brasilia, there is a critical question about the groundbreaking corruption investigation, known by its police code name Lava Jato, that ignited this drama.

As it has unfolded over the past two years, Lava Jato has shattered the historical impunity of powerful figures and inspired Brazilians across the ideological spectrum with a belief that change might be possible in a graft-plagued system.

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There are real fears here, however, that the wild events of the past week have imperilled the investigation, and with it the larger institutional change it has come to symbolize.

Lava Jato is spearheaded by Sergio Moro, a judge in the federal court in the southern city of Curitiba. He has risen from obscurity by pursuing an investigation that began with what appeared to be a minor money-laundering case involving a former director at the national energy company Petrobras.

The director named names in exchange for a plea bargain and so unravelled a kickbacks-for-contracts scam that prosecutors allege was worth more than $2-billion (U.S.), with a hefty chunk of the cash siphoned off by politicians.

Judge Moro oversaw prosecutions up the chain; the heads of some of the country's most powerful businesses were jailed, and then a sitting senator. And the judge became a folk hero to a population revolted by the bribery revelations, and delighted at his apparent fearlessness and personal rectitude.

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Former president Luiz Inacio Lula da Silva eventually came under investigation in the case. Judge Moro sent police to detain him for questioning two weeks ago and, Brazilians learned this week, tapped his phone calls.

When on Wednesday President Dilma Rousseff seemed poised to offer Mr. da Silva a position in her cabinet – thus shielding him from Lava Jato, because a case against a minister can only be heard by the Supreme Court – the judge released the audio of tapped phone calls.

They include one between the current and former presidents that, prosecutors say, shows the intent to obstruct justice.

And with that, Judge Moro himself became the subject of polarized debate.

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"There are a lot of even right-wing legal scholars who think that Moro went too far: He lost popularity with intellectuals with this," said Ivar Hartmann, a professor of constitutional law at the Getulio Vargas Foundation, a Rio university. "But he only gained with the general population."

Fabio Wanderley Reis, emeritus professor of political science at the Federal University of Minas Gerais, said the "judicial subtleties are lost" on much of the population. "Many people do not question the legitimacy of his decisions of the last few days," he said, but rather view the contents of Mr. da Silva's startlingly frank (and profanity-laced) conversations with an array of political figures as ample justification for their release.

Ms. Rousseff reiterated Friday that she sees Judge Moro's decision to release the calls as a deliberate attempt to undermine her democratically elected administration.

"I'm in favour of seeing all corrupt people who have committed crimes go to jail," she said at a public event in the northeastern state of Bahia. "But I'm not in favour of someone arguing that in order to get rid of corruption, democracy has to go, too."

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Prof. Hartmann said he suspects Judge Moro probably now realizes the decision to release the audio so hastily (just three hours after some of it was recorded) was a mistake.

Certainly that decision will come under intense legal scrutiny; three separate complaints have been lodged with the national body that governs judges.

The wiretap order had already expired when one of the key calls between Ms. Rousseff and Mr. da Silva was made. But Judge Moro released it anyway, which Prof. Hartmann characterized as an "appalling" decision. The judge also released a considerable quantity of taped audio, 80 per cent of which should have been kept private, the professor said. And prosecutors indicated that they had edited some of the calls, but not all of them, raising questions about why they omitted what they did.

The national newspaper Folha de Sao Paulo, which has called for Ms. Rousseff's resignation and is sharply critical of the government, nevertheless condemned the release of the tapes in an editorial Friday. "Even though the PT strategy of shielding the former president in the Esplanada [government headquarters] is repulsive, it's not fit for a judge to ignore the rites of the law in order to block what, without doubt, is a bigger evil," the editorial said. "That's what Moro did when he allowed all access to the wiretaps and transcriptions that, as a rule, should be sealed."

Joaquin Falcao, a professor of law who is a former member of the National Judicial Council, said he does not believe any of this will disrupt Lava Jato. "The investigation will proceed normally," he said. "Nobody can say that the credibility of Lava Jato has been affected by Moro's decision [to release the tapes.] The question now is larger than Moro."

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He believes the judge was motivated by a strategy that has guided the investigation all along – of maximum transparency – and that there is no basis to argue that he was motivated by politics. "Yes, he has a personal agenda: fighting corruption. It's not a political agenda. There will be a bit of damage to his [reputation] but it will not affect the investigation."

Prof. Hartmann said he also expects Moro will stay at the helm of Lava Jato, and that the case will stay in his court. "I think he's untouchable now."

The National Judicial Council can (and should, in his opinion), sanction him for overstepping, but is unlikely to remove him, Prof. Hartmann said.

And while some Supreme Court justices have already indicated that they are concerned about the release of the calls by a Federal Court judge, they are unlikely to view it as sufficient reason to remove him either. "Moro made worrying and high-impact mistakes – but the overall result is that judicial independence in Brazil is doing what it is supposed to be doing."

Prof. Wanderley Reis described Brazil's judicial system as having a "social bias" – Mr. da Silva once characterized it, in a campaign speech, as "A poor man who commits a crime goes to jail, and a rich one goes to cabinet."

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Now, Lava Jato has shifted that power balance in ways that may outlast the recent events, he said – newly emboldened prosecutors will not be cowed, even should Judge Moro's investigation stop.

"The promise of Lava Jato is that practice become precedent, part of the law," he said. "But there are very risky potential consequences, in this turmoil."

Investigation details

Editor's Note: The original newspaper version of this article and an earlier digital version incorrectly said Ivar Hartmann is the co-ordinator of a Rio think tank on jurisprudence called the Center for Justice and Society.

In addition, the arrest of a Brazilian senator in the Lava Jato case was ordered by the Supreme Court, not Judge Sergio Moro, as was incorrectly stated in the earlier versions.

This digital version has been corrected in both places.