You can't seem to turn the television news on at present without seeing black-and-white pictures of past horrors - Buchenwald last week, Belsen this, and Hiroshima and Nagasaki still to come in August.
More than a million people died under the Khmer Rouge rule
There was a time when we thought that killing on an industrial scale might be a thing of the past; but, depressingly, the pictures are no longer just in black and white nowadays.
It may be 32 years since General Augusto Pinochet's men began killing left-wingers in Chile, and 30 since the Khmer Rouge arrived in Phnom Penh to force the entire population out into the killing fields.
But it's only 11 years since Rwanda, and 10 since the Bosnian Serb general, Ratko Mladic, ordered the murder of every male Muslim in Srebrenica.
And in Darfur people are dying right now.
Haven't we learned anything? Are we no further forward than we were 60 years ago?
At least 100,000 people are thought to have died in Darfur
We have learned some things. We even have some valuable case law, from the Nuremberg trials to the Truth and Reconciliation Commission in South Africa.
But we haven't yet managed to persuade those who think they can slaughter people as a matter of policy that they will inevitably pay a price for doing so.
True, there is justice sometimes. Killers from the Bosnian war are now serving long sentences.
Gen Pinochet may not be in jail, but he has not been able to live untouched by the consequences of what he did.
The Argentine military leaders who ordered the deaths of 15,000 young people in Argentina between 1976 and 1982 have rarely been free of problems.
Some form of tribunal is expected to get under way in Cambodia this year.
Many of those who took part in the Rwandan genocide have been arrested.
No real consensus
Yet Gen Mladic and his political master, Radovan Karadzic, the president of the Bosnian Serbs in the early 1990s, are still at liberty, in territory where Nato troops operate freely.
Karadzic (left) and Mladic are still at large
No-one has yet convinced President Robert Mugabe of Zimbabwe that he will be held to account for destroying his country and ruining the lives of his fellow citizens.
He has been a welcome guest in France, and was at the funeral of Pope John Paul II in the Vatican last week, even though tens of thousands of Zimbabwean Catholics are being oppressed.
Part of the problem is that there is still no real consensus about what constitutes a crime against humanity.
Some people think Argentina and Chile are better off without the generation of left-wingers who disappeared in the 1970s.
There are those who think that people like Gen Mladic and President Mugabe and those behind the Janjaweed in Darfur have merely had a bad press.
The United Nations has been pretty feeble at dealing with crimes against humanity, because few subjects have more political resonance.
An organisation which is so subject to national political considerations is scarcely the best place to deal with such crimes.
But we do now have the International Criminal Court (ICC) at The Hague, which can investigate and prosecute people for genocide and war crimes.
It was set up in 2002, and has its own judges and its own chief prosecutor, Luis Moreno Ocampo, who took part in the trials of Argentina's former military junta.
When the Court was established by an international conference in Rome, only seven countries voted against. They included China, Israel, the United States, and Saddam Hussein's Iraq.
American hostility towards the ICC, which is based on fears of politically motivated (in other words, anti-American) prosecutions, has lessened slightly as a result of the Darfur crisis.
It eventually agreed to let those accused of atrocities in Darfur be tried at The Hague, as long as Americans and people from other countries which have not ratified the Court would only be tried in their home countries if they too were accused of war crimes.
But the result is that only three years after the ICC came into being, it is already subject to the same kind of national pressures which have stopped the UN dealing effectively with crimes against humanity.
The other week I went to the première in London of Hotel Rwanda, a film about one man's efforts to save people from the genocide there in 1994.
It was beautifully acted, well written, cleverly filmed, and it brought back so many memories of my time in Rwanda.
Of wandering through an empty nunnery whose inhabitants had been raped and murdered. Of trying to find a place to sleep in rooms where the floor was covered with recent blood. Of the terror in people's faces. And of the heroism of a few, like the manager of the hotel, who saved many lives.
But has Hotel Rwanda been a success at the box-office? Guess.
It takes more than shaking our heads over old television pictures of piles of bodies to make sure that these terrible crimes aren't repeated.
Governments will never take enthusiastic action unless they think we really care about these things.
Read John Simpson's previous columns:
Those who have been prosecuted for war crimes are only those who were "foolish" enough to attract attention to what they were doing. Quiet, long forgotten genocide victims, such as the Muslims in Gujarat, Vietnamese Agent Orange victims, among millions of others, will never get their recognition or justice.
Alok, Bangalore, India
Its time for the British public to demand an enquiry into the failures of the UK government to face up to its inaction during the genocide in Rwanda. It is not enough to remember we MUST learn from our mistakes so that it might not happen again in another place and a different time.
William Tucker, University of Wales, Aberystwyth
An article by John Simpson on war crimes and yet no mention of Iraq - how predictable of him to play it safe, yet again.
Like Mr Simpson, I have recently watched Hotel Rwanda. Throughout the movie one thought kept going through my mind - how dare we, the Westerners, call ourselves civilized? Misters Presidents and Prime Ministers - you may not have wielded the machete in Rwanda and you may not be starving the people in Darfur but you make ME ashamed to be Western.
Annette Zammit, Colombo, Sri Lanka
ICC is a lovely idea but until you have the criminals in captivity you can't prosecute them. The UN has shown itself to be completely incapable of meaningful action against murderous regimes and it seems that only military intervention effectively puts them out of business.
Gherkin, Orpington, UK
I agree with all of this article, having watched Hotel Rwanda last week, I yet again found myself having the circular debate about genocide and intervention, playing god. What I would like to know is Mr Simpson's opinion on what could really be done, how do people like myself show that we care about these matters, when subjects like fox hunting are the major political debates in the UK?
Venetia Spencer, London, UK
History teaches us that human nature is bleak, hard and cold. We are genetically programmed to try and secure the survival/ pre-eminence of our own tribe, by whatever means necessary. That is why people will never stop killing and it is the duty of the UN to intervene to prevent human tragedy happening in places such as Darfur.
Emma Fraser, London
Why don't you mention Israeli atrocities in Palestine and Qana of Lebanon? What about Deir Yassin? Now the world calls those reacting to Israeli atrocities and stealing land terrorists while they are freedom fighters. What did the UN and world do about the US vetoing any act of justice? And they consider themselves the heroes of justice and democracy.
Maleeha Maalouly, Beirut, Lebanon
Legal rules and principles are there. However, more often than not, they are either not applied or only selectively and partially applied due to political expediencies. Unfortunate but this is the reality.
S. Rabiee, The Hague, The Netherlands
I was deeply offended by the comparison of the horrible genocide of the Jews during the Holocaust at Bergen-Belson and Buchenwald to the American bombings of Hiroshima and Nagasaki. America was ruthlessly attacked by Japan, and was prosecuting that war to a finish. All powers bombed cities during World War II.
Philip Gerretsen, Buffalo, United States
As a descendent of grandparents killed by the Nazis in Germany, I fear that the same could happen again. Sadly the UN and others that nominally police the world are too removed from the problem, have their own agenda and are too tied up in red-tape/politics to make anything happen fast - even if all parties agree. The rest of the world knows that - but, sadly, has no other mechanism to help stop the atrocities and enforce a return to 'normal' civil rule
Mark Katz, London, UK
No one could argue that we have eliminated crimes against humanity, but all efforts to eliminate impunity for those responsible are very important. The International Criminal Court and a more rigorous intervention policy by the UN are examples of initiatives that must proceed. Those who give the orders must learn that they are not free from accountability. It's a step...
Gary Ockenden, Nelson, CANADA
Have we learnt anything? The simple answer is NO. As long as we can still kill each other and then look back in retrospect at it and say that was horrible, and then try to bring the responsible party to justice, history will repeat itself. I will say that we have learnt the past lesson when we take active role to prevent these acts from taking place, and when we stop questioning the value of every human being regardless of their colour, religion, sex, or personal beliefs.
George, ST. Louis, MO, USA
As long as world power "singular" is looking the other way and ignores what is not in its own interest and sees itself immune from atrocities, I'm afraid our children will see many many more of these killing fields in the future.
Fari Jannati, Leeds, UK
What is Israel's excuse for voting against the International Criminal Court (ICC) at The Hague? Is it because the Likud government is frightened that Sharon will be indicted (and convicted) of war crimes?
Michael, London, UK
I agree with John Simpson's article. I may comment further here. The politicians at the top, who pretend to represent the people of a country must put the brakes on their ego-centric mind and work for the universal cause. In present day world politics, the only universal personality is Kofi Annan of the UN.
Dr. D. S. Malla, Bremen, Germany
I am a Chilean social worker woman and I am very impressed with your interesting point of view and comments about the effects on human rights from dictators and oppressive governments around the world. I think that in our country we are learning these lessons and we are preparing now to defend the civil freedom of expression and we have a conscience about the value of democracy. Congratulations, your analysis is complete and interesting.
Orietta Marambio, Chile
John Simpson is right that the ICC is flawed because it is subject to political pressures, which will result in "victor's justice"-the opposite of what is intended. Until the ICC is independent of politics, and able to subject every single country in the world, and every single head of state, without exception to its judgements it will remain a pale mockery of what it should be. Politicians think they can get away with it because they can!
Another thoughtful article by John Simpson. What can the simple citizens do for governments to believe we care about stopping war crimes? What would it take for political parties to stand up?
Karl Maenz, Geneva, Switzerland
As a nation are we guilty of war crimes in our conduct in Afghanistan, Iraq and other counties? Have we aided the United States and others to take prisoners to torture in Afghanistan, Iraq and Guantanamo Bay? Are our hands clean? I believe that we are guilty and some of our political leaders should be in the dock in the Hague.
David May, High Wycombe, Buckinghamshire
I really appreciate Mr. Simpson's article with respect to bringing war criminal to courts of justice so that the future generations will take note of it. However, I wonder why Mr John Simpson, who worked for a prolonged time in Afghanistan, did not shed some light about Afghan war criminals, who enjoy their lives in the West now. Isn't the West harbouring war criminals, particularly Afghanistan's? I'm sure, everyone heard the name of a war criminal Zardad, who tortured, ill treated and killed so many innocent Afghans. Why is the world so silent? I wonder why.
Beedil, Kabul, Afghanistan
My father was General Telfod Taylor, one of the chief prosecutors at the Nuremberg trails. Every time I read articles about current war crimes, crimes that I feel any reasonably educated person should be outraged at, I feel terrible. Terrible that my fathers life's work at preventing future war crimes back in 1945 has not had more of an impact on future generations. Why is this so hard a lesson for us to learn?
Samuel Taylor, Brooklyn, NY-USA
Intelligent, concise analysis with the right blend of logic and humanity. An island of sanity. Thank you.
Lowell Courtney, Portrush, Northern Ireland
In John Simpson's brief summary of six decades of atrocity, its astonishing to see no mention whatsoever of Vietnam. Conservative estimates say at least two million Vietnamese were killed in their own country. Untold thousands of these people were women and children. After one of the very few cases actually brought to court, Lt. William Calley served precisely three days in jail for massacring 504 innocent, unarmed villagers, many of them literally babies. It's hard to believe all this has slipped John Simpson's mind, and I'm wondering why he didn't mention it. Nothing even remotely comparable has happened in Bosnia or Zimbabwe, for instance.
Patrick Lanagan, Berlin, Germany
John Simpson's excellent articles are fair and dispassionate. But on the altar of brutality and recent genocides he seems to have forgotten King Leopold's barbarity in the Congo and the British terror in Kenya during the Mau Mau. He ought to read King Leopold's Ghost and The British Gulag.
Syl, New York
The fact that genocide still exists today is a sad fact that confirms the darker side of human nature. The only international institution remotely capable of dealing with this issue, the United Nations, is totally impotent in the face of such atrocities. The Arab voting block has dominated the resources and agenda of the UN for decades, and there is no light at the end of the tunnel. The UN has a credibility issue when it comes to its management and its ability to adhere to any kind of moral compass.
Shep Fargotstein, Memphis, TN - USA
It is still money that decides who lives and who dies in this world. The superpowers turn a blind eye to countries where murder of innocent people is done whole sale, so long as it doesn't hurt their economic interest. That is the sad part of this situation, if a country's government's actions cause an economic slump in the US dollar, then the US will invade or have the leaders killed. If the all mighty dollar isn't affected then do whatever you want, is the standard policy of the superpowers.
C.B. Evans, North Carolina USA
The ICC is a noble idea but who presents the suspects for trial? History has taught us that stopping war crimes and punishing the guilty almost always requires armed intervention. Belsen, Aushwitz, Cambodia, the Balkans and Iraq all required troops to go in, stop the killing and arrest or kill the perpetrators. In Darfur, the killing will go on until someone (almost certainly western soldiers) goes and stops it. Those who by default protest against any form of armed intervention should realise that their actions will probably cost innocent lives, not save them.
Although everyone declares that historical events such as the Holocaust must never be repeated, genocide, as we can see, is taking place every day and no one in any position to stop it seems to care unless they have ulterior motives, such as profit or resources. If there is nothing but human lives to gain from intervening, then there is just no authoritative interest in helping. If we are to learn from our mistakes and prevent history from repeating itself, this must stop.
Helen, Essex, England
The US bombing of Cambodia killed hundreds of thousands and is by most accounts a war crime, but receives no mention. Nor does Mr Simpson mention the use of chemical weapons across Vietnam by the USAF. Why not? And how is it the US thinks it reserves the right to avoid any prosecution simply because whereas the cases it pursues are about 'justice' any case against the US is about 'political' or 'anti-American' plots? The whole point of a world court is that all stand before it as equals.
Robin Tudge, London
As always Mr Simpson has it right. However, the horrific grainy images from the Armenian genocide committed at the hands of the Ottoman Empire between 1915 and 1923 illustrate the way that not only the Turkish government but also those of the UK and US deny such atrocities have happened. We still are silent about the 1.5 million people who were erased because it is not politically expedient to make Turkey admit their role in the first genocide of the 20th century. As long as we continue to ignore the past we shall certainly ignore it when it happens on our own doorstep.
John Simpson struggles to find glimmers of light in the gloom - and there is very little light. However, until such a time as politicians (and their electorates) come to terms with the idea that only direct military intervention will prevent genocide and mass murder, the world will continue to stand by as thousands are slaughtered. Meanwhile, we will have unedifying spectacles such as the UN Security Council engaging in sophistry to determine whether what is happening in Darfur is genocide or not, as it did for Rwanda. I am sure the victims' families appreciate their hard work.
Brian Connor, Brussels, Belgium
Every country has a mirror to hold up to itself before it should condemn others. For example China who is trying to condemn Japan for how it treats its past. China has seemed to have forgotten already what they have and are doing to this day to Tibet and its people. And now the good old USA is getting a reputation as a human rights abuser in its prisons in foreign lands. When is the human race going to wise up and live according to laws of what Thomas Jefferson called Nature's God are what most decent people call basic human values.
Elwyn Hudson Jr., Gardendale Alabama, USA
I firmly believe that there is nothing stopping a massive genocide as the Holocaust in the future. People are ignorant and you know what they say, 'Ignorance is bliss'. Tragic but true. These are the ingredients to such horrors:-ignorance, fed by deceit on a mass scale, only bears fruit to horrific consequences.