The importance of this moment is difficult to overstate. The arrest of Saddam Hussein, responsible for genocide and crimes against humanity, opens up the real possibility that justice can be done. The fact that he has been taken alive is crucial; a dead Saddam might have been seen by some as a martyr. As a wanted man in the dock, the details of his brutal rule can be exposed.
Saddam's crimes, including the slaughter of more than 100,000 Kurds in 1988, have been well documented, not least by Human Rights Watch which has analysed 18 tons of incriminating documents that were airlifted out of Iraq in 1991.
Justice, however, must not only be done, it must be seen to be done. Any sense that Saddam might be exposed to victors' justice or revenge justice would lessen the chance of true stability in Iraq.
The International Criminal Court (ICC), which came into existence last year to prosecute the Saddams, Milosevics and Pinochets of the future, can only hear crimes committed since 1 July 2002, and therefore does not cover Saddam's most serious offences. Even without the involvement of the ICC, international involvement is essential. It is right that the Iraqi people should have ownership of the process but it is regrettable that the law on a war crimes tribunal in Iraq makes little provision to involve international judges.
Part of the problem is the loathing that the US feels for international justice, as reflected by its desire to throttle the ICC at birth. The Iraqi Governing Council, eager not to upset Washington, set out its plans for a war crimes tribunal just last week. The new law does not require international judges to sit alongside Iraqi judges on the hugely complex cases which will follow, including the trial of Saddam himself.
That is regrettable, just as it is regrettable that the death penalty has been retained. International expertise could be essential to ensure that justice is done. The example of the Romanian dictator Nicolae Ceausescu - shot after a summary trial in 1989 - reminds us how things should not be done. That execution hindered long-term justice in Romania.
The celebrations after Saddam's arrest should not overshadow the importance of ensuring that we see full due process once he goes on trial. Anything else would be a disservice to the memory of his hundreds of thousands of victims.
Steve Crawshaw is the London director of Human Rights Watch.