As a battle wages on between Congress and the Department of Justice over Robert Mueller’s report, investigators for the special counsel appear to be taking a stand. But what will it take in order for politicians – and the public – to see their findings?

A new report describes “simmering frustrations” at the special counsel’s office after attorney general William Barr released a four-page summary of its findings, effectively concluding Donald Trump was cleared of any criminal misconduct.

Those investigators have told associates Mr Barr’s summary is far from comprehensive and that it undermined the damaging material against the president included in their report, according to the New York Times. It is one of the first reported times the special counsel’s investigators have spoken out about the handling of the investigation in its aftermath.

As the House Judiciary Committee threatens to subpoena the full report from the Justice Department, it seems clear at least some factions of the Democratic Party will not be satisfied with a heavily-redacted report that lacks substantive detail about Mr Mueller’s investigation.

The Independent spoke with several constitutional law experts to better understand what might come next in this potentially lengthy legal fight. Here’s what they had to say:

Mueller investigation: The key figures Show all 12 1 /12 Mueller investigation: The key figures Mueller investigation: The key figures Robert Mueller is the special counsel overseeing the investigation into Russia's meddling in the 2016 election, and potential obstruction of justice by the president. Mr Mueller has a pristine reputation in Washington, where he was previously in charge of the FBI. Throughout his investigation, he and his team have been notoriously tight lipped about what they know and where their investigation has led. REUTERS Mueller investigation: The key figures Former FBI director James Comey was the catalyst that led to the appointment of special counsel Robert Mueller. Mr Comey was fired by the president after Mr Trump reportedly asked him to drop his own Russia investigation. Mr Trump has long maintained that the investigation is a "witch hunt". AFP/Getty Images Mueller investigation: The key figures Deputy attorney general Rod Rosenstein had authority over the special counsel investigation for much of the two years it has been active. Mr Rosenstein found himself with that responsibility after then-attorney general Jeff Sessions recused himself from that oversight. AP Mueller investigation: The key figures Attorney general Jeff Sessions's decision to recuse himself from oversight of the special counsel investigation may have cost him his job in the end. Mr Sessions resigned last year, after weathering a contentious relationship with Donald Trump who vocally criticised his attorney general for taking a step back. Mr Sessions recused himself from the oversight citing longstanding Justice Department rules to not be involved in investigations overseeing campaigns that officials were apart of. AP Mueller investigation: The key figures Attorney General William Barr is currently responsible for oversight of the special counsel investigation. Mr Barr's office will be the first to receive the Mueller report when it is finished. His office will then determine what portion or version of that report should be delivered to Congress, and also made public. EPA Mueller investigation: The key figures Michal Cohn is the president's former personal lawyer, who has been helping the special counsel investigation as a part of a plea deal over financial crimes, and campaign finance crimes, he has pleaded guilty to. Among those crimes, Cohen admitted to facilitating $130,000 in hush money payments to adult film actress Stormy Daniels during the 2016 campaign. Cohen has said he did so at the direction of Mr Trump. Cohen has also admitted that he maintained contacts with Russian officials about a potential Trump real estate project in Moscow for months longer than Mr Trump and others admitted. The talks continued well into 2016 during the campaign, he has said. AP Mueller investigation: The key figures Stormy Daniels has alleged that she had an affair with Donald Trump in 2006, soon after Melania Trump gave birth to Baron Trump. The accusation is of particular importance as a result of the $130,000 hush money payment she received to keep quiet about the affair during the 2016 campaign. AP Mueller investigation: The key figures Paul Manafort was Donald Trump's former campaign chairman. Manafort was charged alongside Rick Gates for a slew of financial crimes, and was convicted on several counts in a Virginia court. He then pleaded guilty to separate charges filed in a Washington court. Manafort has been sentenced to just 7.5 years in prison for his crimes — in spite of recommendations from the special counsel's office for a much harsher sentence. AP Mueller investigation: The key figures George Papadopoulos was one of the first individuals associated with the Trump campaign to be charged by the Mueller probe. He ultimately received a 14 day prison sentence for lying to investigators about contacts he had with Russian officials. AP Mueller investigation: The key figures Roger Stone is a well known political fixer and operative, who has made a name for himself for some dirty tactics. He has been charged by the Mueller probe earlier this year, and he has been said to have had prior knowledge that WikiLeaks planned on publishing stolen emails from the Hillary Clinton campaign in 2016. Getty Images Mueller investigation: The key figures Rick Gates was charged alongside former Trump campaign chairman Paul Manafort for a range of crimes. Gates, who worked alongside Manafort for a pro-Russia Ukrainian political party. The two were charged with conspiracy and financial crimes. Gates pleaded guilty. AP Mueller investigation: The key figures Former national security adviser Michael Flynn was one of the first casualties of the Russia scandal, and was forced out of his position in the White House weeks after Donald Trump took office. Flynn pleaded guilty in 2017 to "willfully" making fraudulent statements about contacts he had with Russian officials including former Russian ambassador to the US Sergey Kislyak. Flynn then lied to Vice President Mike Pence about that contact. REUTERS

Does Congress have legal authority to subpoena the full Mueller report?

“As part of its oversight authority, Congress certainly has the right to request, and even subpoena, the entire report,” said Steven Schwinn, an associate professor of law at the John Marshall Law School. “That said, Justice has authority to determine that some portions of it should not be turned over, or should be turned over with protections. If Congress and Justice disagree, Congress can sue to enforce a subpoena, and the courts can work it out.”

There’s just one problem with that, however: courts don’t typically like to get involved in these sort of disputes between the legislative and executive branches.

“Generally courts have expected Congress and the president to solve this the old-fashioned way, and I believe that’s what will happen here,” said Peter Margulies, a law professor at Roger Williams School of Law. “Based on what the courts have previously done, they have generally allowed the inter-branch process to take its course, so I’d be surprised if the courts were inclined to second guess what the executive has provided – as long as there is some good-faith attempts to provide Congress what they want.”

So how much of the Mueller report can – or should – be redacted?

That question really depends on who you ask. Legally speaking, there are some caveats as to what the public cannot access from the special counsel’s findings.

“There are the two obvious restrictions that would certainly be an open invitation for a redactor's magic marker: grand jury information which ordinarily is under seal … then there’s information classified due to sources and methods used by the intelligence community, which may reveal how counterintelligence operations are being conducted,” said Ross Baker, a professor of political science at Rutgers University.

The White House has also suggested components of the report may be subject to executive privilege, meaning they discuss private details of the presidency’s internal processes and therefore could be withheld from the public – potentially setting up a legal challenge.

Say the courts are forced to get involved. What happens then?

“The courts can order Justice to turn over the redacted portions, or deny Congress’s request for the redacted portions, or maintain some redactions but order release of others,” Mr Schwinn said. “The way the courts get involved, and how they make decisions about the material, will depend on the reasons why Justice is redacting.”

“For example, the courts will judge an assertion of executive privilege differently than they’ll judge an assertion of grand jury secrecy – just because those are two different things,” he added.

Still, legal experts say it’s more likely than not that a resolution will be made between the branches.

“I’d hope attorney general Barr would be forthcoming in providing the vast bulk of the report … I’m still inclined to give him the benefit of the doubt,” Mr Margulies said. “It wouldn’t surprise me if at least some people aren’t happy, but I hope Barr will release enough so it makes clear what Mueller’s thinking was and answers some questions raised from his summary, particularly the obstruction of justice issue.”

How do the House subpoenas play into all of this?

Put simply, the subpoenas may be more of a scare tactic in order to get officials to comply with congressional demands.

“I would like to know the last person who was sent to jail for being held in contempt of Congress,” Mr Baker quipped. “The president can just invoke executive privilege – a lot of these subpoenas will likely be contested based on executive privilege.”

Still, issuing subpoenas sets the legal framework for Congress to uphold its oversight responsibilities under unusual circumstances.

“Congress and the administration usually come to some kind of agreement before a court has to rule,” Mr Schwinn said, describing an example in which the Justice Department makes a single copy of the report available in a secure room where lawmakers can read it one at a time without staff. “But if it comes to negotiating something like this, expect the negotiations to be quite tough,” he noted, adding: “Democrats in Congress will want to be able to point to actual and publicly available text to support their public statements about the content of the report. Justice and Republicans, on the other hand, will want just the opposite, so that they can say that Democrats are making it up. Of course, nobody in Congress yet knows what’s precisely in the report. So they’ll be negotiating in the dark. Which I guess just make this all the more interesting!”

Is there a chance the Mueller report could be leaked?

In spite of Mr Mueller’s team being extraordinarily silent throughout their investigation, it appears more likely now than ever that investigators will speak out if they believe the report’s true findings are not outlined in what the Justice Department eventually provides Congress.

“It looks like somebody is leaking some information that cuts against attorney general Barr’s summary of the Muller report, apparently because they think the summary doesn’t do justice to the entire report,” Mr Schwinn said. “I suspect we’d see more leaks like this – and perhaps the entire report – if AG Barr or someone else at Justice is either seriously misrepresenting the report, or redacting it in a disingenuous way.”

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Mr Baker echoed those comments, saying he could see a leak happening “very easily” if what Mr Barr releases is “a complete over distillation of the findings and in no sense reflects the complexity of the investigation.”