A principle applied in administrative law. The principle as initially recognized by the courts was confined to legitimate expectation of procedural protection (Schmidt v Secretary of State for Home Affairs  2 Ch 149 (CA). A procedural legitimate expectation arises where a public authority has induced in someone affected by a decision a reasonable expectation that he will be granted a hearing or that some other procedure will be followed before a decision depriving him of some benefit or advantage is taken. A failure to act in accordance with the expectation and provide procedural protection is challengeable on judicial review (Council of Civil Service Unions v Minister for the Civil Service  AC 374 (HL). More recently the courts have extended protection to substantive legitimate expectations. A substantive legitimate expectation is an expectation induced by a public authority that an individual will be granted or retain some substantive benefit. A failure on the part of the public authority to act in accordance with the expectation is considered to be a breach of the rule of law that requires predictability and certainty and is therefore * ultra vires (R v North and East Devon Health Authority, ex p Coughlan  QB 213 (CA). The expectation must be based on either an express undertaking or arise from past conduct on the part of the public authority in order for it to be recognized as legitimate or reasonable (AG for Hong Kong v Ng Yuen Shiu  2 AC 629 (PC). See natural justice.