The US Supreme Court will rule in 2020 on a set of historic cases involving Donald Trump that will define the presidency for decades to come and determine whether he can continue to keep his tax and financial records secret.
Mr Trump is battling Democrats in Congress and a New York City prosecutor to stop them investigating his business affairs with subpoenas to his accountant and two lenders, Deutsche Bank and Capital One.
Though the president has been defeated in the lower courts, in March his lawyers will try to persuade nine justices on the conservative-majority high court to endorse Mr Trump’s expansive argument that he has immunity from investigation while in office.
Here’s what you need to know:
What cases will the Supreme Court hear?
Two involve House Democrats, who are investigating Mr Trump’s business affairs and possible Russian influence, and the third involves the Manhattan district attorney, Cyrus Vance, who is investigating alleged hush money payments.
In all three, investigators issued subpoenas for copies of Mr Trump’s financial records to various companies that have worked with the president and his businesses. The president sued the companies — accounting firm Mazars USA and banks Deutsche Bank and Capital One — to stop them from complying with the subpoenas.
What is Mr Trump arguing?
In the US, both parties have long argued that the president occupies a unique role in the constitutional structure. The president is the only elected official in the entire executive branch — one of three coequal branches of government — and therefore requires some protection from interference and distraction while fulfilling his or her duties.
Mr Trump has advanced two separate but connected arguments that rest on this foundation: that he is absolutely immune from any form of criminal investigation while in office, and that House Democrats do not have a valid legislative reason to look into his affairs. Rather, Mr Trump claims, the requests are just efforts to harass him.
The immunity line extends a longstanding justice department policy that considers the president immune from indictment by federal prosecutors while in office. But that has never been affirmed by the courts, nor has it ever applied to investigative steps before indictment.
Taken together with the president’s defiance of the impeachment inquiry, the arguments amount to a broad declaration that Mr Trump, as head of the executive branch, cannot be investigated by anyone as long as he remains in the White House.
How have courts ruled so far?
Most of the judges who have heard Mr Trump’s arguments have responded with scepticism, even apparent disdain at times, as they have repeatedly ruled against him at the district and appeals court level.
Two weaknesses in Mr Trump’s position that judges have noted is that the subpoenas issued by House Democrats and Mr Vance concern the president’s personal affairs, rather than sensitive government matters, and the subpoenas were issued to third parties, rather to the president himself.
Rather than interfering with his duties as president, the subpoenas do not require Mr Trump to produce documents, appear for testimony or “lift a finger”, said David Strauss, a professor at the University of Chicago Law School, who was a lawyer for Bill Clinton in his Supreme Court battle in the 1990s.
“Trump doesn’t have to do anything . . . the burden falls entirely on the banks and accounting firms,” he added.
There are areas where the president could be on stronger ground, however.
Though the Supreme Court has repeatedly affirmed the right of Congress to investigate whatever it wants in order to fulfil its legislative and oversight functions, the court has also weighed the question of whether that power might be misused.
The idea that congressional investigators might use their powers to hobble executive branch officials for purely political reasons is not so far-fetched, said Mr Strauss. Though he said he did not view the current situation as harassment, “that argument in the abstract is not an empty argument”.
What is the historical precedent?
There are three key Supreme Court decisions that have set the scope of presidential immunity in modern times, two involving Richard Nixon and one involving Bill Clinton. The rulings have given the president mixed protections in civil litigation, while not resolving the question of criminal probes.
In US v Nixon, the Supreme Court ruled unanimously that the president had to turnover evidence for a criminal trial in response to a subpoena. A later, less well-known case, Nixon v Fitzgerald, found in a 5-4 split decision that the president was absolutely immune from civil liability for official acts he took in office. And in Clinton v Jones, a unanimous court ruled that the president could face civil lawsuits for non-official actions that occurred before he took office.
How might the Supreme Court rule?
The court is split 5-4 between conservatives and liberals. Two of the conservatives — Brett Kavanaugh and Neil Gorsuch — were appointed by Mr Trump himself, and a key question will be whether John Roberts, the chief justice, can find a way to achieve consensus on such a fiercely political case.
In US v Nixon and Clinton v Jones, appointees of the presidents involved in those cases ruled against them as the court presented a united front. When the court hears arguments in March, close attention will be paid to whether Mr Kavanaugh and Mr Gorsuch will follow in those footsteps.
“The contrast if the court were to divide along partisan lines here would be especially bad for the court,” said Mr Strauss.