On the face of it, Monday’s 9 to 0 “per curiam” ruling from the US supreme court appeared to be one of those rare moments when consensus returns to America, an indication that when the chips are down the country can still achieve an elusive harmony.

Amy Coney Barrett put it most succinctly in her concurring opinion. Pointing out that all nine justices had agreed to overturn the Colorado supreme court’s decision to remove Donald Trump from the presidential ballot, she urged Americans to take home the message that “our differences are far less important than our unanimity”.

That’s a tempting thought at a time when US consensus appears to be breathing its last and the supreme court itself is mired in partisan infighting. It is also entirely misleading.

The justices’ unanimous agreement is the easy bit. All nine conclusively decided that individual states do not have the power to disqualify a candidate for federal office – if they did, chaos would be let loose in a “patchwork” of state-based outcomes.

But Colorado was only one half of the issue before the court. The other half is arguably far more important in terms of the ongoing health of America’s democracy – accountability.

The 14th amendment of the US constitution is all about accountability. Proposed by Congress in 1866 just a year after the end of the civil war, it was designed to prevent former Confederate officers from returning to power despite their rebellion.

Fast-forward 158 years, the circumstances are different, but the conundrum remains the same: should Trump, having attempted to subvert the democracy upon which the union depends, be held accountable and barred from ever holding federal office?

There is a heavy irony on this side of the question. Monday’s supreme court ruling was handed down on the very day that Trump had initially been set to go to trial for his efforts to overturn the 2020 election results.

That date has now been pushed back – dangerously so, many observers believe – by the actions of the same US supreme court which, by agreeing to hear arguments on Trump’s claim that as former president he is immune from prosecution, appears all-too willing to play his delaying game. So if accountability for insurrection is not yet available in the form of a criminal trial, what about accountability under the 14th amendment?

According to the three liberal justices on the court – Ketanji Brown Jackson, Elena Kagan and Sonia Sotomayor – Monday’s ruling should go down as a dark day for American democracy. In their concurring opinion they argue that, with the sole exception of Barrett, the conservatives have in effect defanged the 14th amendment.

Not content to overturn the Colorado decision, the five conservative justices go on to deliver their own unexpected – and in the liberal justices’ view, wholly gratuitous – reinterpretation of the amendment. They state that for it to be enforced, Congress must first pass “implementing” legislation.

Nothing in the amendment’s text says anything about Congress needing to pass such legislation. In fact, as the liberal justices emphasize, the 14th amendment is one of the so-called “reconstruction amendments” framed in the immediate aftermath of the civil war, and as such is “self-executing” – meaning that it can be applied without any need for congressional approval.

It requires little contemplation to know what the conservatives’ imposed formula of prior congressional action means in practice. It means no action.

When Trump faced his second impeachment trial over inciting insurrection at the US Capitol on 6 January 2021, all but seven Republican senators voted to acquit him. Then there are the 147 Republicans in Congress who voted to overturn the 2020 election results on that same fateful day.

Most of the analysis of Monday’s decision will focus on its immediate implications in terms of Trump’s 2024 presidential run. But the sting of the ruling – and its danger, despite its unanimous facade – is likely to be felt in the longer term.

As the three liberal justices lament, the ruling shields the court and “petitioner” – ie Trump – “from future controversy”. Worse, the conservative majority has moved to “insulate all alleged insurrectionists from future challenges to their holding federal office”.

That is a devastating charge. It accuses the chief justice, John Roberts, as well as Samuel Alito, Neil Gorsuch and Brett Kavanaugh, as well as Clarence Thomas whose wife, Ginni, is deeply implicated in the 2020 stolen election conspiracy, of protecting all future insurrectionists against the democratic safeguards built into the US constitution.

That future may not be long in coming. Trump has shown no remorse over 2020, and may well unleash another attack should he lose in November.

And after Trump? Could a more formidable Trump 2.0 emerge, one whose chances of success have been enhanced by Monday’s per curiam ruling.