Leading article: A landmark ruling for international justice

It will cost in excess of £39,000 a year to imprison Charles Taylor in a British jail after he is sentenced by the UN-backed Special Court for Sierra Leone next month. But the longer the sentence – and the more it therefore costs the British taxpayer – the more pleased we should be. It is money well spent.

The former Liberian President was yesterday convicted of 11 separate war crimes and crimes against humanity for his role in fuelling the savage decade-long civil war in neighbouring Sierra Leone. The list of offences is bad enough, including terrorism, murder, rape, cruelty, pillage, sexual slavery and turning children into soldiers. The gruesome details revealed at the trial – the tales of human intestines strung across roads, the severing of tens of thousands of human hands, the claims of ritual cannibalism – are more appalling still. That a central figure behind such crimes has been brought to justice is progress indeed.

Of even greater significance, however, is the milestone the case marks in the effort to ensure that even the most powerful individuals may be held to account under international law. As the first conviction of a former head of state since the Nuremberg trials, Taylor's sentence sends the clear signal that even those in the highest positions are not untouchable.

By agreeing to house the convict in a British prison, the UK has played a vital role in ensuring that justice be done. Indeed, without such an agreement from the then Prime Minister, Tony Blair, Taylor's trial in The Hague might not have gone ahead at all. The offer – which was also made with regards to the Serbian dictator Slobodan Milosevic who died before his case was completed – was an important symbol of Britain's commitment to the international rule of law.

Sad to say, Taylor's guilty verdict was greeted with a sigh not a cheer in Sierra Leone yesterday, any satisfaction at the conviction tempered by disappointment that the warlord was condemned on only the least of the three charges he faced. While the court could have found that he exercised "control and command" over the atrocities, or that he was involved in the offences as a "joint enterprise", it ruled only that there was sufficient legal proof that he "aided or abetted" the crimes.

The Taylor case also raises some serious procedural issues. Critics claim that the poor timing of the original indictment, in 2003, gave Taylor cause to intensify the conflict, which thus claimed thousands more lives. Given the parallel accusation that the International Criminal Court indictment of President Omar al-Bashir of Sudan may have, similarly, made things worse in Darfur, there is a strong argument for prosecutors to consider their timing more carefully.

Questions must be asked, too, about whether international justice really need take so long to reach its conclusions. It is almost a decade since the Special Court for Sierra Leone was set up; Taylor's trial took close to five years; and the judges deliberated for 13 months before delivering yesterday's verdict. Such glacial progress is not only vastly expensive. It also hardly instils the necessary confidence.

But so comparatively new, and awesomely complex, an endeavour as the establishment of international criminal procedures was never going to be easy. For all the criticisms and caveats, the most important point is still that the so-called Big Men who have held sway in Africa – and in the Balkans and the Middle East – for so many decades have witnessed an hour of reckoning at last. No longer can they rest easy in the comfortable assumption they may do as they please, however atrocious, without fear of the consequences. Position and power place no warlord above the law. With the conviction of Taylor, the days of impunity are over.