Washington (CNN) The US Supreme Court now stands at the precipice of a constitutional clash that could determine whether Donald Trump or any future President may elude an investigation and defy requests for documents.

Depending on the extent of the court's moves, it could influence Congress' oversight authority for the ages.

The nine justices could act as soon as Friday in the dispute tied to Trump's effort to withhold his tax returns and other financial records. His lawyers contend that subpoenas by a US House committee and the Manhattan district attorney are unprecedented and have warned of an "open season" on the President. But lower court judges, relying on long-established precedent, have refused to block the subpoenas.

Now, with the impeachment inquiry hearings for the week over, suspense in Washington is building over how the justices -- five conservatives and four liberals -- will handle this pair of cases.

The looming separation-of-powers questions tied to Trump's finances began before the House of Representatives initiated the impeachment inquiry related to the Ukrainian dealings. But any Supreme Court resolution of the cases could influence evidence available in a swath of House actions against Trump and would certainly color this politically charged moment in American history.

"The House's rapidly advancing impeachment inquiry," House lawyers told the justices in a Thursday filing , "... makes it particularly important that Congress not be deprived of the information sought by the subpoena."

Trump's lawyers in a filing earlier this week insisted that never before has a President been subjected to a subpoena asserted under Congress' legislative authority but intended "to investigate the President for illegal conduct."

The Supreme Court should intervene, they say, "not to benefit this particular President but for benefit of the Presidency itself."

They contend that unless the high court throws out the subpoenas related to Trump's personal finances and rules for him on the merits of the controversy, he and all future presidents would be hounded by political enemies and distracted from executive duties. The US House and New York investigators who want to enforce the subpoenas have urged the justices to outright reject the Trump pleas and avoid breaking any new ground regarding presidential immunity.

These disputes on financial records are the first to reach the Supreme Court, but won't be the last. Multiple lawsuits testing Trump efforts to keep documents secret and block associates from testifying are ongoing.

Pressure on the court

The Trump-records controversy has landed at a high court already ensnarled in the politics of the day and at the edge of the impeachment drama. The polarization in Washington is reflected on the bench.

The justices often divide 5-4 on political and ideological lines, and Chief Justice John Roberts, who has himself sparred publicly with Trump , has increasingly tried to offset public criticism by saying the justices are motivated by law not politics.

Roberts is likely to tread cautiously and try to avoid a 5-4 split, if at all possible. The justices to his right (Clarence Thomas, Samuel Alito, Neil Gorsuch and Brett Kavanaugh) have been unyielding proponents of executive authority and deferred to the Trump administration on cases, generally over protests from those justices on the left (Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor and Elena Kagan).

Unlike other thorny disputes that come to their doorstep, the justices have little leeway here to postpone action, as they have done for months with difficult appeals on issues such as abortion and immigration.

Trump is challenging subpoenas whose enforcement could be imminent, particularly by the US House Committee on Oversight and Reform, which has sought Trump financial records dating to 2011 from his accounting firm Mazars USA as part of a re-examination of ethics laws. His lawyers have made an emergency request, asking the justices to block Mazars from being forced to turn over the records.

In the second case, Manhattan District Attorney Cy Vance is looking into "hush money" paid to women who claimed affairs with Trump. This subpoena specifically requests Trump tax returns among records from 2011 to the present. (Trump has denied the affairs.)

The justices also face a crowded calendar of cases testing LGBTQ protections in the workplace, immigration and abortion rights. Further, if the House votes to impeach Trump, Roberts, according to the terms of the Constitution, would preside over a Senate trial.

Roberts' appearance in the Senate could be more of a ministerial than substantive role, based on past episodes. But it nonetheless will bring the chief justice into the orbit of impeachment controversy.

'Intrusive subpoenas' and Congress's right to investigate

The new cases could embroil all nine in impeachment-related dilemmas and test any new constitutional protection for Trump.

Trump's arguments against the House Committee on Oversight and Reform could be consequential for any future congressional scrutiny of a President.

His lawyers argue that if the House were allowed to enforce the subpoena for financial records, as lower court judges say it can, any committee would be able to force presidents to turn over information simply by saying it is considering related legislation.

"Given the temptation to dig up dirt on political rivals," Trump's lawyers wrote, "intrusive subpoenas into personal lives of Presidents will become our new normal in times of divided government -- no matter which party is in power."

House lawyers cast the dispute more narrowly, saying the subpoena for information from Trump's longtime accountants "is intended to shed light on the accuracy of President Trump's disclosures" and help inform the committee on ways to write new ethics legislation that would cover all candidates.

They argue that courts have routinely upheld such subpoenas and that the justices should not allow presidents to determine the timetable for when a committee can obtain information relevant to a House inquiry.

If the justices were to intervene in this case, they could face a constitutional minefield as they determine what documents Congress could seek from a President and what might be off-limits.

The US Court of Appeals for the District of Columbia Circuit that upheld this order directed at Mazars cast it as easily covered by Congress' entrenched subpoena power.

Lawmakers, the House lawyers added, don't have unlimited time for judges to review individual challenges over documents or potential testimony.

"(I)t cannot be the case that the President has the right to stall any Congressional subpoena to which he objects through the months or years that it takes for a challenge to work its way through the lower courts and for this Court then to grant or deny (a petition)," House lawyers wrote.

"If that were the case, the House -- which has only a two-year term -- would be radically constrained in its ability to conduct oversight or to collect information about the Executive Branch," they added.

The dispute arising from Manhattan District Attorney Vance's attempt to obtain tax records for a grand jury proceeding presents a narrower legal question, although Trump's lawyers have made a broad-based argument that a President should be shielded from any criminal proceeding while in office.

Ruing against Trump, the New York-based 2nd US Circuit Court of Appeals declared only that "presidential immunity does not bar the enforcement of a state grand jury subpoena directing a third party" that is, Mazars, "to produce non-privileged material, even when the subject matter under investigation pertains to the President."

The court grounded its ruling in the 1974 United States v. Nixon Supreme Court decision that required President Richard Nixon to turn over the Watergate tapes.

Trump's lawyers want a new categorical prohibition against subjecting a President to a criminal proceeding, even at an early investigative stage. They have asked the justices to look beyond the New York dispute, arguing that the question is not whether the current subpoena arising from so-called hush money paid to women during the 2016 presidential campaign would now distract Trump.

The question they say, "is whether allowing every state or local prosecutor to target the President for criminal investigation" would encroach on the executive. "It clearly would," the lawyers say.

In the Vance team's response to the justices late Thursday, it minimized the significance of the case, saying "the grand jury here is performing a garden-variety investigation of purely private conduct."

They urged the justices to stay out of the dispute: "Whatever interests might counsel in favor of review where there are substantial, open questions regarding presidential immunity, they are not present here."

The New York subpoena is on hold under a timetable set by both sides in this case if the Supreme Court takes the dispute up for review in the current session, which ends in June 2020.