The law relating to relevant and irrelevant considerations has developed substantially in the UK.
The decision of a public authority is subject to judicial review if the authority took into account irrelevant considerations in arriving at its decision.
If a court wishes to categorise an error as jurisdictional it can do so by using the 'wrong question' or 'irrelevant consideration'formula.
Note that the improper purpose or the irrelevant consideration must be such as to materially influence the decision.
That it assaults the reputation of one outside the House is an incidental and irrelevant consideration.
This, the court said, was an irrelevant consideration which rendered his decision unlawful.
It is silly to allow irrelevant considerations to stand in the way of making a rational and fair decision.
The gossipy brouhaha surrounding it rendered its literary merit a secondary, perhaps even an irrelevant consideration.
This does not mean, however, that the effects of competition are always an irrelevant consideration.
I agree with those people who have regretted that the whole debate has been hijacked into an entirely irrelevant consideration about duty-free.