(CNN) – The Supreme Court will hear three cases on Tuesday that present its most important exploration of the separation of powers in decades. The disputes test the ability of the US House of Representatives and state prosecutors to investigate a president, arising from stalled efforts to obtain financial records from President Donald Trump.
The records sought trace to allegations of misconduct before Trump became president, and the disputed subpoenas were issued to his accountants and banks, not to the President directly. Trump intervened to try to block the subpoenas; he lost in lower courts.
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The current Supreme Court is split between five Republican-appointed conservative justices and four Democratic-appointed liberals. Chief Justice John Roberts rejects criticism about politically infused decisions. These cases will challenge that assertion and could color how the public views the court for years to come.
Here are six things to watch for as the justices hear Trump's appeals:
Will they buy Trump’s arguments to broadly shield the President?
The justices are likely to spend much of their argument time delving into the nitty-gritty of presidential immunity and subpoena authority, but a fundamental question looms: Is the President is off-limits?
Will the justices, particularly Trump appointees Neil Gorsuch and Brett Kavanaugh, reveal sympathy or skepticism for core arguments to protect the President from scrutiny?
Oral arguments, especially in the current rigid teleconference mode, do not always reveal the justices' true sentiment. But after months of lower-court litigation on these momentous issues, the public might finally hear whether the high court is willing to accept Trump's far-reaching positions or, conversely, ensure that House committees and state prosecutors can obtain materials for their investigations.
The challengers say Trump's position would put him "above the law."
Are the justices thinking beyond Donald Trump?
Right now, a Republican is fighting off subpoenas from a Democratic-led House of Representatives. In the near future, the political players could be reversed.
With an election on the horizon, will the justices' questions suggest concern about the broader reverberations of curtailing House power, or will they regard the House position under any circumstances a "blank check" to pursue a president?
Much of the current controversy traces to Trump's unique decision to keep ties to private business interests. Past presidents divested their holdings or used blind trusts. House lawyers have argued that Trump's global financial interests have generated distinct conflicts. Yet it is not hard to imagine future clashes with different presidents in the sights of congressional committees.
Is there middle ground between Trump and Congress?
Between the President and House Democrats, the justices may seek some middle course. House lawyers contend the subpoenas issued to Trump's longtime accountants and banks are vital to core legislative purposes as they craft new anti-corruption law, and they say the court owes Congress deference in the legislative endeavor.
Trump and his lawyers characterize the subpoenas are part of a fishing expedition into his private records and warn that if the House prevails in these disputes, politically motivated subpoenas would be routinely enforced.
The Justice Department, aligned more with Trump than the House, attempts to offer the court a middle ground that would permit subpoenas but set a "heightened" standard for when they are justified. Department lawyers argue that any subpoena would have to be approved by the full House, not only by investigative committees as occurred in these cases. They also insist the legislative purpose asserted must be particularly detailed and clearly pertinent to the stated purpose. If the justices bite on a "heightened" standard, the crucial query would be how precisely that is defined, and could the House ever satisfy it.
Will the justices try to avoid a ruling in the House dispute altogether?
There is a chance the justices will punt, finding that the House committee controversy is too political for judges to resolve.
Two weeks ago, the court asked the parties to address whether the court should avoid any decision because of the "political question doctrine or related justiciability principles." That suggested some justices thought the political nature of the cases could prevent them from ruling, and perhaps those justices might follow up with questions on Tuesday. Lower court judges found no such barrier to reaching the merits of the constitutional dilemma and both sides of the current dispute recently told the court it has no grounds to opt out.
Certainly, justices may silently wish they were not handling a Trump-House faceoff in a presidential election year. But the cases mark a crucial constitutional test of Congress' oversight authority.
How far might the justices go to favor Trump in a criminal investigation?
In the dispute over a New York grand jury's subpoena, Trump's lawyers say a president should be absolutely immune from criminal investigation while in office. During oral arguments before a US appeals court last year, Trump's lawyer, responding to a question invoking Trump's famous claim, said immunity would extend even to shooting someone on Fifth Avenue in New York.
That extreme stance related to any criminal investigation extends the Justice Department's guidance prohibiting indictment of a president and conflicts with Supreme Court precedent. Manhattan District Attorney Cyrus Vance counters that the grand jury wants routine materials from Trump accountants and insists such third-party request would not interfere with his duties. (The request flows from a probe of so-called hush money paid to women during the 2016 presidential campaign who said they had affairs with Trump.)
Still, there may be concerns among the justices about prosecutors in 50 states investigating a president. The Justice Department, again, has offered a test that would favor the President but not go as far as his lawyers want. It says a prosecutor should have to show that the materials sought were "essential" to an investigation.
Will Chief Justice Roberts unite the bench?
An axiom of today's Supreme Court is that tough cases come down to Roberts, the conservative justice closest to the ideological center of the nine. These three disputes present an even greater imperative for a chief justice who has made plain his concerns about the court's integrity.
The two overriding touchstones for such presidential controversies were decided unanimously. They are the 1974 case of US v. Nixon, rejecting an executive privilege claim and requiring President Richard Nixon to turn over the Watergate tapes; and the 1997 case of Clinton v. Jones, spurning an assertion of presidential immunity and subjecting President Bill Clinton to a civil lawsuit by Paula Jones, who said he had sexually harassed her when he was governor of Arkansas. Roberts would be aware that justices in those cases worked to find common ground and avoid predictable political divisions.
Will Roberts send any early signal on Tuesday about the dilemma for the justices in the public eye? He insists that the justices do not rule as Republicans or Democrats, but "decide cases according to the Constitution and laws without fear or favor."
Will he pursue some narrow approach, toward possible unanimity, or, at least, an outcome that that avoids the 5-4 classic split that defines the Roberts Court?