If Trump obstructed justice, what next?
The latest Washington parlour game is trying to determine whether or not special counsel Robert Mueller is currently investigating Donald Trump for obstruction of justice in the Russia election meddling inquiry.
Mr Trump's lawyers have denied it. The president himself seemed to confirm it. Mr Mueller isn't talking. All this speculation misses the bigger question, however. What happens if Mr Mueller not only is looking into possible criminal misdeeds by the president, but he ends up finding them?
Such a prospect opens a legal Pandora's box - but it's one Mr Mueller should probably be pondering. Here are some possible what-next scenarios if that smoking gun (or guns) turns up.
A report to Congress
The traditional means of addressing presidential criminality - if "traditional" is the right word, given that it's a path explored only three times in US history - is through impeachment proceedings in the House of Representatives followed by trial in the US Senate.
Impeachment requires a simple majority vote, while it takes a two-thirds majority in the Senate to approve removal. It is, as is frequently noted, a political act first and foremost, where the grounds for action are essentially whatever Congress decides.
If this is the course Mr Mueller pursues, his investigation into the president may end with a report to the Justice Department, which could then be passed along to leaders in Congress. There's no legal requirement for it ever to be made public, although the pressure on politicians to do so will be enormous.
That process would track the course set by Ken Starr when looking into possible misdeeds by President Bill Clinton in 1998. In that instance the independent counsel concluded that the then-president may have engaged in criminal behaviour. He provided his supporting evidence to Congress to do with as it saw fit.
They impeached, but there were not enough votes to convict in the Senate.
Indictment and trial
What Mr Starr decided not to do with his investigation was seek a criminal indictment of the president. But while conventional wisdom is that this option is foreclosed, there are some differing views in the legal community. While the constitution is clear about impeachment proceedings, it's silent on the subject of bringing criminal charges against a sitting president.
"It is an open and substantial question whether an incumbent president is subject to indictment," Watergate special prosecutor Leon Jaworski told Supreme Court justices when they were considering whether to grant a subpoena for President Richard Nixon's Oval Office tape recordings.
Mr Nixon resigned before he was impeached and was subsequently pardoned by President Gerald Ford, but the special prosecutor had named him an "unindicted co-conspirator" in its case against several of the president's aides.
Those who think a presidential indictment is impossible tend to point to the impracticality of indicting someone who has the legal authority to pardon himself, as well as a passage in the constitution that states removal from office through impeachment doesn't preclude criminal charges.
That suggests, they say, the founding fathers envisioned any criminal proceedings should only take place after a president is out of power.
Giving the judiciary the ability to sanction a sitting president also could implicate the constitutionally crafted separation of powers between the three divisions of US government - the executive, the legislative and the judicial. Judges are in the branch the least accountable to US voters, the argument goes, which is why the founding fathers put the power of removal in the hands of Congress, with members who have an electoral mandate.
Susan Bloch, a constitutional law professor at Georgetown University who has studied the legality of presidential indictments, says the prospect of a president standing trial and then possibly being sentenced to jail while still technically in office is "ludicrous".
"You should not be subjecting a president to a criminal procedure while he's president," she says. "The text [of the Constitution] suggests it, but I think the practical considerations to me say you don't want to make a president worry about a criminal proceeding."
While the US Supreme Court held that a sitting president could be subjected to a civil trial in Jones v Clinton - the sexual harassment case brought by against President Clinton that eventually led to his impeachment - the penalties in such cases are monetary, not possible jail time.
Bloch adds that the Supreme Court underestimated just how damaging even a civil proceeding could be to a presidency. During Mr Clinton's subsequent impeachment, the nation's business ground to a halt. A presidential criminal trial would be orders of magnitude more disruptive.
When dismissing the legality of a presidential indictment during a recent television interview, one of Mr Trump's personal lawyers, Jay Sekulow, also cited Justice Department policy guidelines dating back to the Watergate scandal.
"The indictment or criminal prosecution of a sitting president would be unconstitutional because it would interfere with the president's ability to carry out his constitutionally assigned functions and thus would be inconsistent with the constitutional structure," read the report from the Justice Department's Office of Legal Counsel.
Mr Mueller, as a Justice Department employee, may be bound by these guidelines, which would end the debate over indictment before it really begins.
Supporters of leaving a president subject to criminal charges counter that the case for temporary presidential immunity is based on a subjective interpretation of constitutional provisions. If the founding fathers had wanted presidents to be effectively above the law until they left office, they would have explicitly said so.
They also have their own practical arguments in favour of immediate criminal proceedings. Deferring prosecution until after a president leaves office, for instance, could make the task more difficult. Evidence could be lost or destroyed, and witnesses could die or forget important details.
Professor Eric Freedman, in a 1999 Hofstra Law Review article, notes that other administration officials - including the vice-president - have been subject to indictment while in office. Some federal judges have been tried and sent to prison prior to removal by Congress.
"Reading the Constitution to insulate an incumbent president from criminal liability would not only feed the imperial delusions to which too many high officials in this century have succumbed, but would undermine the fundamental concept of the president as an ordinary citizen temporarily exercising power delegated by 'we the people'," he writes.
An indictment on hold
A third possible resolution was floated in that Office of Legal Counsel memo, although the Justice Department ultimately rejected it. Could a grand jury issue a presidential indictment, then put the trial on hold until after the chief executive leaves office?
That would certainly avoid the spectacle of a sitting president in the criminal dock, but it would allow the wheels of justice to begin turning. The Justice Department's view, however, was that the resulting political cloud would surely be toxic.
Given "the realities of modern politics and mass media, and the delicacy of the political relationships which surround the presidency both foreign and domestic," the Justice Department wrote in its 1973 report, there would "be a Russian roulette aspect to the course of indicting the president but postponing trial, hoping in the meantime that the power to govern could survive".
Even someone as apparently bulletproof as Mr Trump would be hard-pressed to survive such a spectacle.
It wouldn't take long for Mr Trump's opponents, for instance, to dust off old quotes from the Republican's presidential campaign in which he warned of the dire prospects of Hillary Clinton assuming the presidency while the target of a criminal probe.
They would certainly appreciate the irony, bitter though it may be.