In some circumstances, the Court will find that a claimant has a ‘legitimate expectation’ that a decision-maker will keep a promise that it has made or will continue its past practices. In these cases, the Court may quash a public authority’s decision where it would be unfair to allow the public authority to break its promise or to change its practice.
There are two broad types of legitimate expectation – procedural legitimate expectation and substantive legitimate expectation. Procedural legitimate expectation arises where a decision-maker makes a promise to do particular things during the decision-making process, or has consistently done particular things in the past.
Substantive legitimate expectation arises less often. It arises where a decision-maker has made a promise to an individual or specific group of people that they will be granted a particular benefit (or that it will continue to be enjoyed).
A legitimate expectation may be defeated by an overriding public interest reason (e.g. the need for a government department to keep within its spending limits).