The question has come to the fore now that the House Committee investigating the events surrounding that day has started to lay out the evidence it has gathered.
In effect, the committee is building a case, a case for the prosecution. But the committee will not and cannot decide who gets prosecuted. Its job is simply to investigate and report what it finds.
Prosecutions are the responsibility of the US Department of Justice, and its political head, the Attorney General.
Earlier this week, there was a classic Washington insider debate over whether the committee should issue a recommendation to the justice department that it mount a prosecution.
Committee members have not considered the question formally. The committee chair, Bennie Thompson, a Democrat from Mississippi, said it was not their role to recommend prosecution.
But deputy chair Liz Cheney, a Republican from Wyoming, said the committee could issue such a finding, and may well do so.
In fact, it may not be necessary and could even be counterproductive, inviting charges of a political witch-hunt.
Luckily for the committee, it is not a choice they have to make.
It is up to the Attorney General, who earlier this week told reporters he is watching every minute of the committee proceedings (not necessarily live) but prosecutors in the justice department are also watching, to see if anything turns up.
Plenty has already, and they won't have to wait much longer for the full account.
Key findings so far:
- Donald Trump lost the presidential election in 2020 and he claimed there had been fraud.
- He was told he had lost fair and square by his closest advisers, even after investigation by the Attorney General.
- He challenged the result in court (60 times) and lost every one of them.
- He persisted with the claims of voting fraud and irregularity (the so-called steal) and fastened on another route to victory.
"Stop the Steal" was a legal theory propounded by lawyer John Eastman, emerging as a key figure in the process, that the US vice president could somehow use hitherto unknown powers to change the result of the election and may even be enough to bring charges.
Ms Cheney, the daughter of former vice-president Dick Cheney, appears to think so.
In a video put out on social media on Wednesday to stoke interest in the latest installment of the committee's work, she said: "President Trump Plotted with a lawyer called John Eastman and others to overturn the election on 6 January - as a federal judge has said, this likely violated two federal statutes".
One of the biggest surprises the committee has thrown up so far was an email from Mr Eastman to Mr Trump's personal lawyer, Rudy Giuliani, asking to be included on a "pardon list".
It was sent on 11 January last year, a week after the storming of the Capitol.
This suggests that he was, at the very least, concerned that what he had been doing might have been illegal.
The committee has also played, several times, a video clip of Eric Herschman - a White House lawyer hired by Mr Trump to defend him in his second Senate impeachment trial - and kept in by the Oval Office afterwards.
In the clip Mr Herschman describes a conversation with Mr Eastman held on 7 January, the day after the riot.
When Mr Eastman pressed on with his argument about electoral problems, Mr Herschman deployed unparliamentary language to tell him his plan was "crazy", and told him he was going to give him the best free legal advice he would ever get in his life.
"Get a great F***ing criminal defence lawyer, you're going to need it," he said.
Legacy of the 'stolen' votes
Towards the end of the week, the US Attorney General asked the committee to share its transcripts with the justice department to help it prosecute a number of individuals it is currently investigating.
The latest conviction in relation to the storming of the Capitol came on Friday, when Couy Griffin, the founder of a group called Cowboys for Trump was sentenced to 14 days in jail and fined $3,000.
But his real significance is that he is a county commissioner in his home state of New Mexico, where he is refusing to certify the results of last Tuesday's primary elections in Otero county until there is an investigation into the voting machines there; the same type of machines that Mr Trump and his officials said were the cause of voting "irregularities" in the presidential election (a claim found to be untrue).
The Federal Prosecutor in New Mexico has asked for an FBI investigation into Mr Griffin's refusal to certify the election and an online fundraiser has raised $50,000 for his legal defence.
It is a stark example of the power of the Stop the Steal conspiracy claims, and how they live on long after the 2020 election and the events of 6 January, and even as the house committee lays out strong evidence demolishing the claims.
Also on Friday, former trade adviser to Mr Trump, Peter Navarro, pleaded not guilty to two charges of criminal contempt of congress, for refusing to testify before the committee. His trial was scheduled for November.
Meanwhile Steve Bannon, seen by many as a key strategist in Mr Trump’s world, is going on trial next month for contempt of congress, for also refusing to testify.
The committee said it will make its transcripts available to the Justice Department when it has finished its work, which will be quite soon, possibly next month, for this is not a long drawn-out affair.
Often investigations like this by committees start with a flurry of interest, but then the public loses interest as details are pored over day by day.
Witness statements grind on, and documents unavailable to the watching public are referred to, leaving all but the deepest nerds confused.
Eventually a huge report appears, a summary is furiously debated for a day or two, then ... people move on, often missing the salient features of the report and why it was commissioned in the first place.
Think of the committee investigation into the collapse of the Albert Reynolds government, or various tribunals, notably those on planning and the beef industry.
Watergate marks 50 year anniversary
Here in the US, the gold standard of committee investigations of political affairs is the Watergate committee.
As it happens, this weekend marks exactly 50 years since the break-in at the Watergate complex offices of the Democratic National Committee, and the campaign for the presidency of the party’s candidate George McGovern.
The senate Watergate committee worked largely in public, its televised hearings attracting big audiences in the age of little choice in broadcasting.
Its revelations arrived piecemeal, the drip drip effect wearing down the presidency of Richard Nixon.
When it eventually moved to impeach him, Mr Nixon resigned rather than face trial in the Senate.
Donald Trump has already been impeached, twice.
The charges were ill-conceived and were swatted away by the lawyers, and he beat the rap.
Impeachment proceedings did little to dent his appeal to the electorate.
Indeed, he had already noted his own seeming imperviousness to assault in the court of public opinion during the 2016 presidential campaign when he opined that he could stand in Fifth Avenue shooting people and they would still vote for him.
Impeachment is a political process
A politician is put on trial by other politicians, acting as prosecutor, judge, jury and executioner, and the punishment is intensely political too: loss of office, and disgrace in the history books.
But the 6 January committee is not seeking to mount a political prosecution.
Instead, it is laying out a mountain of evidence which it hopes and expects the Department of Justice will act on.
The committee wants an independent prosecution service to use its evidence to mount a criminal prosecution through the law courts. Which makes this an entirely different process to the Watergate investigation or the previous impeachment attempts against Mr Trump.
The structure of its work is also important.
It has operated for 17 months behind closed doors. Very little leaked about what it was up to, apart from the big numbers, like 1,000 witness interviews and 100,000 documents obtained.
But instead of a daily drip-feed of small, seemingly unconnected information nuggets, and an endless parade of interviews and cross examinations, the committee worked in secret, only revealing what it had found now.
It is revealing its findings in a highly edited, organised, curated manner.
Instead of confronting the public with preliminary hearings, it is confronting them with preliminary findings in its public sessions.
Effectively it has turned the report on its findings into a six or seven-part TV drama and we are almost half way through the season.
This structure means it is much easier for the public to grasp the significance of what is being presented to them.
The importance of the timelines
Who did/said/tweeted what, where and when is rendered much clearer by waiting to exposing a near-complete picture.
Committee members can take it in turns to work through a narrative of what happened, backed up by short extracts from video interviews, and live, in-person questioning of witnesses (but in a closely edited fashion).
They are asked specific questions that they have previously answered in depositions, this is not a trawling exercise, it is extremely sharply focused.
The timing of the installments - in easily digested two-hour chunks, spread out over a couple of weeks in June - is intended to provide enough detail and clear narrative to keep viewers hooked, but not swamp them with detail and digression (and length).
The gaps between sessions may help people to come to terms with what is being presented - especially for those who have chosen to follow the Trump line (almost four fifths of republican voters, according to some recent polling work).
A focused month of findings is also seen as necessary to try to counter the two-year campaign by the Trump campaign to justify its actions.
A one-day event of the publication of a report would not be enough to break through all the other distractions of daily life.
The slow, but not too slow, outlining of the case and evidence against Mr Trump is aimed at converting part of the Republican base away from the Donald Trump narrative.
For that, the committee has relied on testimony from Republicans, and not just any old Republicans, but Trump loyalists, his own appointees, staff, even his own daughter.
Among the most damning - his former attorney general Bill Barr - who stuck with the plan until 23 December 2020.
When it became too much for him, describing how he told Mr Trump it was "bulls**t".
And Judge Michael Luttig, a revered figure in conservative republican circles, whose slow, measured replies to questions slowed down the brisk pace of the committee presentations, as if deliberately designed to underscore the gravity of what this high priest of the secular religion of the US Constitution was saying: that what was being attempted on 6 January was absolutely not allowed under the constitution, that if Mike Pence had caved in and suspended the counting of the votes it would have precipitated a "revolution, wrapped in a constitutional crisis".
The Watergate story was broken by two journalists at the Washington Post, Bob Woodward and Carl Bernstein.
Now, half a century on, the most famous byline in American journalism was back in the pages of the Washington Post.
Woodward and Bernstein had a long article looking back at Watergate and contrasting it with what the 6 January committee is investigating.
They wrote: "As reporters we had studied Nixon and written about him for nearly half a century, during which we believed with great conviction that never again would America have a president who would trample the national interest and undermine democracy through the audacious pursuit of personal and political self-interest. And then along came Trump".
They continued: "The heart of Nixon's criminality was his successful subversion of the electoral process - the most fundamental element of American democracy. He accomplished it through a massive campaign of political espionage, sabotage and disinformation
"Then…. In a deception that exceeded even Nixon’s imagination, Trump and a group of lawyers, loyalists and White House aides devised a strategy to bombard the country with false assertions that the 2020 election was rigged, and that Trump had really won. They zoned in on the January 6 session as the opportunity to overturn the election result".
They concluded that Mr Trump became "the first seditious president in our history", as a result of what happened on 6 January.
But it is one thing for a journalist to claim it, another thing for it to be proven to the level required for a justice department prosecution, let alone a conviction in court.
Will the committee produce the evidence needed for the justice department to act? Will Donald Trump and "all the president’s men" face a court of law?
Obstructing the work of congress seems a more likely charge, and an easier one to prove than sedition. But we are only halfway through the "mini-series" of the committee’s findings.
Stay tuned for the season finale.