IT’S the sheer enormity of the Chilcot report that will be its legacy.

Not just its physical size – though a 2.6 million-word report is certainly large. Not just the amount of time it took to produce – though seven years was undoubtedly too long. It’s the scope that’s breath-taking. Chilcot’s unravelling of the Iraq War, its planning, execution and aftermath, touches on almost every international policy decision taken since and helps explain domestic problems we are still wrestling with today.

Chilcot reveals 2003 to be a massive turning point for Britain and the world. It wasn’t just a regrettable foreign policy blunder that cost the lives of British soldiers and hundreds of thousands of Iraqi civilians, but also a moment of cavalier disregard for democracy that created the preconditions for radicalisation in the Middle East, destabilised everyday life across the world, eroded public confidence in the probity of British government and ended automatic support for the Labour Party in its former heartlands. No matter how much Alistair Campbell shrugs off criticism, John McTernan insists the Middle East was always volatile and Tony Blair repeats he had no option, the alternative version of reality presented by Sir John Chilcot has a real ring of truth about it. At last.

The long-awaited report calmly uncovers the lies of Tony Blair and the shortcomings of UK governance structures – together they produced the catastrophically bad decision to go to war against Saddam Hussein in 2003, before diplomatic efforts had been exhausted. It exposes the autocratic, one-man style of decision-making, the tendency towards dangerous group-think and the lack of real challenge from civil servants, government backbenchers or opposition MPs.

The report also implicitly condemns the politicians (and broadcasters) who have belittled Alex Salmond and his decade-long, one-man campaign to have Tony Blair tried for conducting an illegal war. It explains the steady loss of public faith in Westminster and every other bit of the establishment, and the collapse of confidence within the BBC after Director General Greg Dyke was forced to walk the plank over the “sexed up” dossier fiasco – whose sensational claims were given a more thorough going over by the new findings. All the weaknesses in BBC political coverage – including the indyref – find their origins in that management cave-in to Tony Blair and Alistair Campbell over Iraq.

So what happens next?

If it’s nothing – that’s deeply problematic. A failure to prosecute Blair and others would seem to suggest nothing went dramatically wrong inside Number 10 during the months and years before the 2003 invasion – that the mayhem and carnage that followed were the terrible products of business as usual. Business that’s hardly changed over the last thirteen years.

Of course Chilcot has produced embarrassing revelations – or rather confirmed what many of us believed for years. Tony Blair did privately promise he would back the American invasion before parliament or the cabinet agreed. Blair did ignore advice from the Foreign Office and his government did make “wholly inadequate” plans for the post-conflict situation – leaving British troops under-resourced and without the equipment they needed.

But since Chilcot laid responsibility for the worst post-invasion decisions squarely at the door of the Americans, Blair et al might hope to avoid blame. It’s certainly true that Paul Bremer ran Iraq for 14 months after the invasion as the presidential envoy in charge of occupying forces. It was Bremer who banned members of the Ba’ath party from holding public office and disbanded the Iraqi army – both held to be massive strategic mistakes.

But American excesses do not let Tony Blair off the hook. Bremer told Sir John’s inquiry in 2010 that senior British officials backed his purge of Saddam-era personnel and yesterday’s report observes that Blair “overestimated his ability to influence US decisions on Iraq”.

Still, experts suggest it could prove well nigh impossible to find a court capable of prosecuting the former prime minister. Dr Mark Ellis, executive director of the International Bar Association says international law “has not progressed to a stage” where anyone who breaches the United Nations’ prohibition on the use of force can be brought to justice.

Instead, he believes, the only body competent to try Tony Blair is the UN Security Council and since both the United States and Great Britain are permanent members, that’s simply not going to happen. Lawyers disagree on whether the International Criminal Court in The Hague has the jurisdiction to decide if the invasion of Iraq was a pointless act of war. A spokesperson for the ICC said it would only bring a prosecution if “a state is unable or unwilling to genuinely investigate and prosecute any perpetrators”.

Nonetheless, there may be other routes for prosecution in the British courts. Lawyers representing the family of Dr David Kelly – the government scientist who died after he was exposed as the source of a damning BBC story – says he is considering whether the inquest should be reopened in the light of the Chilcot report.

And, of course, families of soldiers who died in the Iraq war have been taking legal advice on whether Blair and others might face action in the civil courts here. Earlier this week, General Sir Michael Rose, who’s been advising the families, said action might be taken for what he called “malfeasance in public office”.

Misconduct in public office is a common-law offence. The crime, dating back to the 18th century, has been criticised for vagueness by the UK Ggovernment’s law reform advisers. It may be committed when a public officer acting as such, wilfully misconducts himself to such a degree as to abuse the public’s trust in him, and does so without reasonable excuse or justification.

Blair’s critics believe his behaviour amounts to the sort of wilful misconduct envisaged by the judges. But the fact parliament backed his call for military action may count as “reasonable excuse”. Indeed, this legal avenue has the ring of Alistair Carmichael’s recent legal history about it – where lawyers for the Orkney Four argued for an unusual application of the Representation of the People Act – and almost succeeded.

But the soldiers’ families may have to continue without the help of media coverage or publicity. As Jonathan Freedland points out in The Guardian: “At any other moment, Chilcot would’ve been the all-consuming subject of national debate for days or even weeks, with Blair on the rack.

“Now it will fight for airtime alongside the battles for both the Tory and Labour leaderships and the raging argument about how Britain relates to its European neighbours. Blair’s decisions will be exhumed, his reputation may well be flayed once more. But the focus will not be anywhere near as intense as the former prime minister must once had feared.”

It may be up to the SNP – the only Westminster party untouched by internal post-Brexit meltdown – to take the lead again. Alex Salmond could have his hands full for months if not years ahead. But if he and the Iraq relatives find a legal route that works, hundreds of thousands of voters will applaud the chance to make the buck stop with Tony Blair.