The anomaly arises from the fact that the quashing of a conviction does not, in the eyes of the law, prove that the accused did not commit the crime in question. And the state will only pay compensation where a full-blown miscarriage of justice has taken place. A wrongful conviction alone does not qualify.

But a crack appeared in this anomaly yesterday. The Supreme Court ruled on the case of Raymond McCartney and Eamonn MacDermott, whose 1979 murder convictions were quashed in 2007. The judges allowed the two men to appeal against the rejection of their compensation claim. And the president of the Supreme Court, Lord Phillips, argued that the fact that they cannot prove their innocence beyond reasonable doubt should not preclude them from obtaining an award. That is a welcome relaxation. But the threshold of proof for those who wish to claim compensation remains dauntingly high.

An automatic grant of compensation for those whose convictions are quashed would be undesirable. Yet the onus should be on the authorities to argue that an award is inappropriate, rather than a wrongfully imprisoned individual having to fight for their rights. It is better for the state to pay compensation to those who might be guilty than to withhold it from those who might be innocent.

Britain's liberal legal tradition is one of our great national strengths, but we also have a public culture that shades into vengefulness. Even when convictions are quashed, the assumption can persist that the freed individual must have been guilty of some sort of wrongdoing to have attracted the attention of the police. If we believe in the principle of innocent until proven guilty, we must act as if we believe it. That means being prepared to compensate, without complaint, those whose liberty was wrongfully removed.