In Tuesday's historic arguments over President Donald Trump's fight against subpoenas for his financial records, the U.S. Supreme Court justices struggled to find a balance between their worries about potential harassment of presidents and interference with their duties and concerns over how a ruling for the White House could elevate presidents above the law and impede legitimate oversight and investigations.

The court's conservative majority seemed more sympathetic than their liberal colleagues to Trump's challenge to subpoenas by three House investigating committees, but there appeared to be openness across the bench to the needs of a state grand jury investigating possible criminal activity by Trump and his businesses.

"At some point there's a straw that breaks the camel's back," Justice Clarence Thomas told Douglas Letter, general counsel of the U.S. House. "It seems you're saying look at [the subpoenas] in isolation instead of the aggregate and whether at some point, it debilitates the president. It could be every grand jury, every prosecutor. One [subpoena] could be manageable but 100 impossible."

Thomas ended his questioning of Letter, stating, "I think we all know it's about the president."

But Justice Elena Kagan, questioning Trump counsel Patrick Strawbridge of Consovoy McCarthy, said, "It seems to me you're asking us to put a 10-ton weight on the scale between the president and Congress and essentially to make it impossible for Congress to perform oversight and to carry out its function where the president is concerned."

The justices held back-to-back hearings for more than three hours on the president's effort to keep his tax returns and other financial matters secret. Trump was the first president in modern history not to provide the public a copy of his tax returns, despite vowing, then failing, to do so. Trump has given various reasons over the years about why he will not release his returns.

The first set of arguments in Trump v. Mazars focused on the subpoenas issued by three House investigating committees—Oversight, Financial Services and Intelligence. The committees issued the subpoenas to Trump's longtime accounting firm, Mazars, and two of his banks: Deutsche Bank and Capital One. Lawyers for the banks have not taken a public position on the subpoenas.

The oversight committee's investigation stems from testimony by Trump's former lawyer, Michael Cohen, who testified before Congress that Trump inflated and deflated certain assets between 2011 and 2013 to reduce his real estate taxes. The Financial Services Committee is looking into possible Russian money laundering in the president's real estate deals, and the Intelligence Committee is exploring any foreign influence in elections.

The second argument in Trump v. Vance centered on the Manhattan grand jury subpoena to Mazars for 10 years' worth of Trump tax records. The grand jury is investigating whether the president's business records were falsified to hide hush money payments before the 2016 election to two women with whom Trump allegedly had sexual relationships.

Many of the justices' questions in both sessions focused on the various "tests" that the parties argued should be applied to the issuance of subpoenas to the president and the scope and limits, if any, to them.

Arguing for Trump, Strawbridge said congressional subpoenas should be held to a high standard. They should have a legitimate legislative purpose that is defined with specificity. The House subpoenas, he argued, fail all the hallmarks of a legitimate legislative purpose and their demand for decades of papers from the president and his family, he added, "opens the door to all sorts of requests."

Principal Deputy Solicitor General Jeffrey Wall also urged a high standard. "The House must explain in a meaningful way why it needs the subpoenaed records in particular. There is a mismatch between breadth and duration of subpoenas and the asserted purposes," he said.

Ruth Bader Ginsburg Supreme Court Justice Ruth Bader Ginsburg speaks at Columbia Law School. Photo by David Handschuh/ALM

Justice Ruth Bader Ginsburg said the clash of interests in the Nixon Watergate tapes case, the Whitewater special counsel investigation and the Paula Jones civil suit against then-President Bill Clinton were "much more" serious than the cases before the court involving Trump's financial records.

Kagan, picking up on a Ginsburg statement, said, "These subpoenas are for personal records, not for official records where the president might have an executive privilege claim or burden the way the executive branch operates. Why doesn't that suggest a lower standard, not a higher one?"

Letter, counsel for the House, said his test does have limiting principles: subpoenas must be pertinent to a legislative purpose, can't violate a constitutionally protected liberty interests and can't undermine presidential responsibilities.

"Your test isn't really much of a test; it's not a limitation," said Chief Justice John Roberts Jr., "and it doesn't seem in any way to take account of the fact they were talking about a coordinate branch of government, the executive branch."

During one exchange, Justice Brett Kavanagh told Letter: "Just about everything can be characterized as pertinent to a legislative purpose and you couldn't answer something that wasn't. How can we protect the House's need for information to legislate and protect the presidency?"

During the grand jury subpoena arguments, Trump's personal lawyer, Jay Sekulow, argued that the Constitution's Article II and the supremacy clause make the president temporarily immune from all criminal process.

Justice Sonia Sotomayor challenged that argument, saying, "You seem to be asking for broadness of immunity nowhere in the Constitution."

U.S. Solicitor General Noel Francisco, arguing in support of Trump, offered a lesser test or standard. A prosecutor must demonstrate a special need for the subpoenaed information, the same standard that the federal prosecutor in the Nixon tapes case had to meet, he said.

But Sotomayor questioned why that test—drawn from a case involving Nixon's claim of executive privilege—should be applied to this grand jury subpoena when there is no privilege claim and the main concerns are the burden on and harassment of a president. She asked at one point: "Is the investigation based on credible suspicion of criminal activities and the subpoena is reasonably calculated to advance the investigation?"

After Sekulow and Francisco finished their arguments, the court turned to Carey Dunne, general counsel to the Manhattan District Attorney's office. Roberts asked him if there should be a higher standard applied to local district attorneys' subpoenas of a president than applied to House committee subpoenas.

"If there has been an affirmative showing of burden, a prosecutor should show an objective basis for the investigation and a reasonable probability the request will produce relevant information," Dunne said. "The courts below already found we met that standard here. To get permission first for any request relating to a president's business activities would undermine the confidential grand jury process. The other problem is their [test's] language only applies in trial proceedings. No charging decisions are made in the grand jury process."

A decision is expected this summer.