t is right that the allegations of genocide and other crimes against humanity that have emerged from Kosovo in recent weeks should be investigated with angry propriety by the responsible international authorities. Interviews should be carried out with survivors, statements taken, details noted and evidence amassed. Nothing should be assumed to be true, but everything should be open to be proved. The equivalent of police roadblocks should be thrown around Serbia to prevent the escape of suspected criminals from among the mass of the non-culpable population.

The dreadful power of Nato should turn to detection as well as destruction. When the horror has spent itself, the trial of alleged wrongdoers before an international forum should be a sine qua non of any settlement. There should be no waiting 50 years this time, as there was with Sawoniuk. but even if there is, then such prosecutions should occur. Impunity is the enemy of justice, and no killer should be able to rest this side of the grave.

That the Kosovan tragedy is seen so immediately as a human rights issue is a remarkable advance in international thinking in just a very short space of time. When the Balkan wars returned in earnest at the start of this decade, much of the talk was of macro-political matters. The peoples of the region counted not as truly human but as odd-shaped pieces in a complex diplomatic jigsaw puzzle that only experts could solve.

This view has now been transcended by the scale of the Kosovan tragedy. A remarkable feature of the human rights response to the current crisis has been that it has reached well beyond humanitarian hand-wringing and calls for future prosecutions, and directly addressed the Belgrade war machine which is the core power behind the alleged genocide. If it is indeed true that the Nato action is designed to stop international war crimes, much as a police officer would arrest a criminal gang intent on murder, then there has been an extraordinary deepening in our approach to the international protection of human rights. This move towards a more human rights-centred international legal order has been proceeding on a number of fronts. The Pinochet case, the Sawoniuk conviction for war crimes and the handover of the Lockerbie suspects are indications of this, as was the earlier establishment of war crimes tribunals in respect both of Rwanda and the former Yugoslavia and the recent agreement to set up an international criminal court.

If this new human rights perspective is to last, it needs to be protected from political exploitation and consequent public cynicism. It is easy to be moral about human rights when the language suits wider diplomatic and national aims, but righteousness should be an awkward absolute, not a means to an end. Why have the Lockerbie suspects been handed over when no similar investigations have been conducted into the controversial American air-raids on Libya in 1986, which reportedly killed some 37 people and injured 90? If every victim really matters, should not the international community hunt down with equal assiduity those responsible for the killing of thousands of Palestinians in the Beirut refugee camps in September 1982? And is there not now enough evidence to respond more decisively to China's continuing actions in Tibet, and to Indonesia's occupation of East Timor, where the worst army massacre for eight years has just been reported? Does it matter that the Chinese prime minister Zhu Rongji has last week been feted rather than arrested in the US?

The point is not the facile one that Nato should happily bomb the world for a moral end or apprehend world leaders in post. The exposure of double standards is an inevitable part of the process of moving the international order from one set of paradigms to another. But we need to be told what the legal basis is for the bombing of Belgrade, and if there is none, then what are the principles that purportedly legitimise the destruction. Surely it is more than the exercise of raw Nato power? If that is all that it is, why should international law bind only the Serbian government, but not Nato? If China, Indonesia and other human rights transgressors are not to be bombed, as assuredly of course they should not be, what Western response would be proportionate to their alleged assaults on human rights? A new international legal order based on human rights will only operate effectively when it is inconvenient and serves no ulterior aim. In this regard the Pinochet case is the true trail-blazer, since it has been initiated and managed entirely by the judiciary in both Spain and the UK. As such it has been wholly independent of government, and in its processes and emphasis on unglamorous legal argument most closely resembled the paradigm of how international law might with luck gradually develop.

Mirroring this subconscious ambivalence about human rights at the international level is a cultural split closer to home. The British public seems very happy to reach into its pocket to send large sums to Kosovo for the relief of distress. Like the nations bombing Belgrade, we are more than happy to care about human rights where this involves no great inconvenience to ourselves. But human rights is about more than the purchase of cheap moral absolution. We excoriate Macedonia for being unwilling to receive the refugees from across their border without knowing the slightest thing about the country's population, its delicate ethnic balance and above all its poverty. When British citizens of Asian origin were expelled from Kenya and Uganda 30 years ago, we passed special legislation to keep them out, laws later condemned as explicitly racist by the European Commission on Human Rights.

A genuine belief in human rights and dignity has an unavoidable but (for many) unpalatable political dimension. A tiny fraction of our huge wealth goes towards the kind of aid countries such as Macedonia need, but how many of us would willingly pay a new world development tax, or even campaign to free the world's poor from the debt in which the rich West has ensnared them? If more state-backed aid is too much to ask for, what about the civil liberties of refugees? Every year in Britain thousands of asylum seekers are held in detention without charge pending the processing of their applications. Others are deprived of the means of a decent life in this country through the withdrawal of state aid and the throwing of obstacles in the way of their applications to remain here.

While we bomb Belgrade to protect the Kosovans, Parliament is being asked to pass a new bill on immigration and asylum which will make it even harder for those fleeing persecution abroad to be able to settle here. History might judge us as harshly as we judge the Belgrade public now if we turn our backs on those fleeing human rights abuses across the world at exactly the moment when we say that human rights have never mattered more.

Conor Gearty is a barrister and professor of human rights law at King's College, London.