Not the last word

"Whether or not patriotism is the last refuge of the scoundrel, national security can be the last refuge of the tyrant." Lord Walker issued that shrewd warning before going on to side with the government in a landmark case concerning the legality of heavy-handed terrorism laws. While well aware of the scope for abuse, the courts are always reticent about second-guessing the executive on national security; ministers, after all, have special responsibilities and privileged information here. Yesterday, the law lords unanimously displayed the traditional deference. They ruled that it had been lawful to axe a police probe into BAE Systems - a move made, officially, out of concern for public safety.

The investigation into the firm's Saudi dealings was initially sparked after Guardian journalism uncovered evidence of alleged corrupt payments between the arms company and the kingdom. Alleged kickbacks, totalling £1bn, had been paid to the powerful Saudi Prince Bandar, a man closely involved in procuring Britain's biggest arms deal. The British establishment has been involved in channelling and concealing that cash. The implications - for business, for politics and for international relations - could hardly go any wider. But the case came to the attention of the lords yesterday in a particular context - Lord Justice Moses' bold high court ruling in April which held that, by pulling the plug on the probe, the British authorities had neglected their duty to safeguard the law against blackmail.

While closely reasoned, the lords' ruling is thus narrow in scope, specifically departing from the high court in emphasising that the judiciary should only "disturb" independent prosecutors in extreme circumstances. The law lords were especially concerned to defend the Serious Fraud Office's head, Robert Wardle, who effectively had such a role in the BAE case. Certainly, it would have been wrong to scapegoat him - the high court had already established that Mr Wardle had refused to buckle for months, finally folding only after Tony Blair penned a personal minute arguing that pushing ahead would cost lives.

The lords acknowledge such pressures were applied. They do not, however, consider whether they were applied reasonably - only whether Mr Wardle was within his rights to consider them when confronted with them. His thinking may not have been directly tainted by commercial concerns, but it was not the lords' job yesterday to assess whether the advice he received was tainted. The former prime minister has made no secret of having been conscious of BAE's lucrative contracts. And there were, of course, other occasions when the Blair administration put a spin on intelligence.

What the new ruling changes is less important than what it does not. The allegations of bribery stand. The Saudi response to their exposure -namely a blackmailing threat to cut off security cooperation - is confirmed. And yesterday's judgment provides another reminder that the SFO believed it had a robust cases against BAE. What does change, unfortunately, is that there is no longer the prospect of this being prosecuted in English courts.

Despite that disappointment, BAE judicial review has been valuable. Without it, much damning evidence would have remained hidden. Lord Justice Moses may find, as innovative past jurists such as Lord Denning often found when overruled, that his line of thinking will prove to be influential in other contexts. Above all, the outcome should not be taken as meaning that BAE is out of the woods. Its dealings elsewhere - from Tanzania to the Czech Republic - remain under police investigation in Britain. And the Saudi contracts themselves are still being actively looked at, by the US department of justice. The firm may still face its day in court over these, but if that happens it will now be in a courtroom over the ocean.