Once or twice in a reporting lifetime, a journalist is allowed by events to participate in a project that can affect history. The film I have narrated tonight on Channel 4 – Sri Lanka’s Killing Fields – airs at 11.05 pm. It is a painful, and complex team achievement in which we have pieced together an account of what happened in the closing weeks of Sri Lanka’s civil war.

Bluntly, our evidence shows how Tamil civilians were corralled into one ever diminishing piece of land and systematically shelled and bombed by government forces. Some of the targets were medical facilities emblazoned with the internationally recognised Red Cross.

The United Nations believes at least 40,000 civilians were massacred in this process. Our evidence of how it was done comes in the form of mobile phone footage, Tamil and government film footage, and mobile phone “trophy footage” in which soldiers filmed themselves abusing and executing Tamils who had either surrendered or been captured.

War crimes were committed on both sides in what was a barbarous conflict. But the Government action that we report tonight transcends anything seen during this phase of the civil conflict.

It is a harrowing and difficult film to watch. But it represents not only the evidence required to convict, but a first ever testament in the digital age to the dawning truth that in this age it is becoming close to impossible for warring forces to cover up what they have done.

The United Nations own panel of inquiry is already satisfied that a war crime occurred on the scale and of the nature that we report tonight. Whether those responsible are brought to trial at the International Criminal Court, or at the Hague will in part depend upon the pressure from those who see this film upon their own politicians to support the ringing for charges.

Channel 4 is lifting its normal commercial access restrictions to allow the film to be freely seen by anyone anywhere in the world. Additionally, it is bound to go viral via Youtube.

This is not my normal kind of Snowblog. I end by asking you to watch this film. It could well prove a kind of a watershed, a moment when humanity, confronted with the evidence, cries ‘no more’. In our century of war – as the 21st Century is already beginning to feel – this could provide a moment when the perpetrators of war crimes meet the law courtesy of global disgust and pressure.

You will see that the film had to be, as it is, horrifically true to the facts of what happened. I hope you will spare 50 minutes tonight, it could be that it will make a difference.

@jonsnowc4

Sri Lanka’s Killing Fields will be available to watch on 4oD as soon as possible after broadcast. Channel 4 News will also be broadcasting a preview of the film during tonight’s news broadcast.

I have been working in these last few days and weeks on a couple of documentaries. The most important of which is a shocking film showing alleged war crimes in the Sri Lankan civil war.

It will be going out at 11pm on 14th June on Channel 4, and was shown to the UN Human Rights Commission on Friday.

So I wake up this morning ready to focus on another news day and suddenly think what  a strange mix of matter swirls around our world.

On Saturday I had to dash to the Hay Festival – not an easy dash as anyone who has been will know. I did an onstage interview with Mohammed El Baradei on a video link from Cairo – he ran the IAEA nuclear watchdog in Vienna during the build up to the Iraq War – and he talked about endless US interference with his work. I also interviewed Rolf Heuer – an inspirational German particle physicist who runs the Large Hadron Collider at CERN on the Swiss/French border near Geneva.

He never let on, in our fascinating dialogue, that he would today announce that the collider has scored a huge success in capturing and holding “anti-matter” for some sixteen minutes. I’m not even going to try to begin to talk about it here, but I concluded when I spoke to him, that the work of his team at CERN in unravelling the history of the universe will have a profound impact on the future survival of us all. So today’s breakthrough is positive and significant. So that’s the good news.

The bad news is more or  less everywhere else. Gathering storm clouds over the UK economy. The appalling killing of Syrian demonstrators on the Israeli border on the disputed Golan Heights. The continuing slaughter of protesters inside Syria and the chaos in Yemen.

And the strange manoeuvrings of the Chinese navy in the South China Sea. Actually it may be worse than that. China’s Defence Minister says his country is pursuing “peaceful development”. But protesters in two Vietnamese cities this weekend argued otherwise. They accuse the Chinese of attacking a Vietnamese oil exploration boat. And China and the Philippines are at loggerheads over an atoll upon whose beaches both nations have been trying to unload oil drilling materials.

It won’t be the lead story tonight, but I’m beginning to think that this year in our world is one of the most challenging and potentially unstable in many years. So much happening – so little time to report it!

Follow Jon Snow on Twitter: @jonsnowC4

Jon Snow’s article first appeared in the Guardian newspaper.

The scandal of Britain’s libel laws and their facility for libel tourism is well known. So too is our traditionally cavalier attitude to freedom of speech.

But even against this background, the idea that a country with one of the worst records for press freedom and human rights was able to use the UK’s broadcast regulations to challenge legitimate reporting of allegations about cold-blooded killings in a brutal civil war surely takes the UK to a new place.
Whatever private individuals and corporations may be able to do, our legal system does at least prevent states, governments, and political parties from suing for defamation in our courts.

I and my colleagues at Channel 4 News are emerging from a storm that saw Sri Lanka bypass our libel laws and attempt to use Ofcom, the broadcast regulator, to do what the law would not allow – silence our journalism.

Ofcom’s job is to protect “people who watch television and listen to radio from harmful or offensive material” and to further the interests of UK citizens in respect of communication matters. It does this well.

Ofcom’s job has never been to protect governments or organisations from criticisms or to further their political or commercial interests.
 
Last year, we broadcast a video showing nine bound and naked men, two of whom were shot, on camera, by soldiers who appeared to be wearing Sri Lankan army uniform.

On the night in question the script made clear that while we couldn’t authenticate this video, sent to us by a group called Journalists for Democracy in Sri Lanka, it nevertheless raised matters of such importance that further investigation was warranted.

The Sri Lankan High Commission immediately denied the atrocities that the video appeared to show.
 
Two weeks later, at a news conference in Colombo, Sri Lanka said “independent” analysis had declared the video a “fake“.

It mounted a high-profile global campaign to discredit the report, protesting outside Channel 4’s London headquarters. The Sri Lankan government opened up a second front in the UK, filing a series of complaints with Ofcom – one for accuracy and impartiality, one for fairness and privacy.

What had begun as a media campaign to try to destroy the credibility of the Channel 4 News report had become a private battle using the UK’s broadcast regulator. It was a battle in which they were initially allowed to hide anonymously behind the confidential nature of the procedures.

In the end, battle was spared by the findings of a UN committee which recently concluded that the “offending” tape did appear authentic, and dismissed Sri Lanka’s analysis.

Strangely, on the eve of the UN report’s publication the government of Sri Lanka dropped its Ofcom complaints. Whether it had got wind of the verdict, we do not know.

The Sri Lankan video affair has revealed how the Ofcom procedures are potentially open to abuse that threatens to curb not only investigative reporting, but coverage of countries who have repressive and litigious trouble spots and who would rather hide this from public scrutiny.

In short the way Ofcom’s complaint procedures are framed raises serious implications for the reporting of issues of global significance,
 
Ofcom has come of age in my reporting life time and I regard it as an unexpected regulatory success. But we all need to look to the very real risk of governments “hijacking” the regulatory process for their own political ends.
 
In this case, Ofcom was placed at the centre of an international row over Sir Lanka’s human rights record and was being asked to take decisions which could have had a major bearing on the country’s attempts to defend its reputation. This cannot be a proper use of the Ofcom process and nor can this be in the interests of UK public at large.
 
Before Sri Lanka’s complaints were dropped, we were prepared to put these arguments in front of a court.

We felt a clear ruling that denied countries access to Ofcom’s complaints procedures would be beneficial not just too political debate in the UK, but would also help the regulator to avoid being drawn into major international crises. In the absence of a legal ruling, only parliament can change the basis on which complaints can be brought to Ofcom and we urge them to find time to do so. 
 
Without such clarity, we have a serious concern that other countries could follow the Ofcom route.
 
Ofcom surely needs to ensure that Sri Lanka is the last country ever to be allowed to attempt to pervert the regulator’s domestic complaints procedure for its own reputational needs.

spent yesterday afternoon in the environs of the House of Commons. An extraordinary experience.

Normally, ostentatiously crawling with MPs and peers anxious to be recognised, stopped and interviewed – yesterday the place was completely deserted.

The tawdry goings-on have sent many of our legislators running for cover.

What I could not avoid was a huge demonstration on the lawn of Parliament Square – one of the biggest I have ever seen there.

For a moment I thought that the citizenry had come to the barricades to shout ‘enough’ at their MPs.

But no, this was a very unusual demonstration, and one that has been continuing for weeks.

Made up of only one ethnicity and with few others coming to their aid. They are Tamils desperately concerned about the fate of their families and friends in Sri Lanka.

I moved among them and met many. They are in many cases professionals. I met two sisters, consultants at London hospitals. I met engineers, teachers, and shop keepers.

But I also met a terrible sense of despair that we in Britain have neglected their plight and that of the one million displaced Tamils in Sri Lanka.

And I wondered, as MPs tried to wrestle the Speaker from his chair in nineteenth century scenes across the road – how fit for purpose is Parliament? What are its priorities? How far DO we respond to the foreign policy implications and sensitivities of this very sizeable minority in our midst?