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This case, heard in the House of lords Ainsbury v Millington [1987]1 W.L.R. 379, 381) involved a dispute between two joint tenants as to who had a right to occupy a particular property. Court of appeal declined to hear the case, claiming that it was outside its jurisdiction. The reason for this decision was that, as the tenancy agreement had expired, there was no dispute to settle. The Lords upheld this view; the relevant passage in the judgement (p. 381) is

Thus, even if the House thought that the judge and the Court of Appeal had been wrong to decline jurisdiction, there would be no order which could now be made to give effect to that view. It has always been a fundamental feature of our judicial system that the courts decide disputes between the parties before them; they do not pronounce on abstract questions of law when there is no dispute to be resolved.

This case often quoted to stress the practical nature of the English legal system; there are other, similar cases. However, in some cases the House of lords has accepted jurisdiction for cases that no longer express live issues. For example, in R v Secretary of State for Home Department [1999] the Lords ruled on a issue concerning benefits paid to an asylum seeker; the issue had become moot for the appelant, as he had been granted refugee status by the time the case was heard. Despite this, the Lords ruled thus:

...in a cause where there is an issue involving a public authority as to a question of public law, your Lordships have a discretion to hear the appeal, even if by the time the appeal reaches the House there is no longer a lis to be decided which will directly affect the rights and obligations of the parties inter se.

The judgement goes on to say that this discretion should be exercised with caution, and does not overturn the ruling in Ainsbury v Millington, which was essentially a case concerning the obligations between private individuals.