A good question.

In fact really the only question in foreign affairs is this one: Does Bad Behaviour have Bad Consequences?

Now we have one answer in the awesome ruling in the High Court yesterday that HM Government had been wrong in law in blocking corruption investigations under official pressure from Saudi Arabia:

The context of the threat, in the present case, was the investigation of making bribes to foreign public officials, an offence introduced in 2001. If the Government is correct, there exists a powerful temptation for those who wish to halt an investigation to make sure that their threats are difficult to resist. Surrender merely encourages those with power, in a position of strategic and political importance, to repeat such threats, in the knowledge that the courts will not interfere with the decision of a prosecutor to surrender. After all, it was that appreciation which, no doubt, prompted the representatives of the Saudi Arabian government to deliver the threat. Had they known, or been told, that the threat was futile because any decision to cave in would be struck down by the courts, it might never have been uttered or it might have been withdrawn.