Wednesbury reasonableness limits judicial review to illegality, procedural defects, or irrational administrative decisions. Wednesbury reasonableness restricts judicial interference to illegality, neglect of relevant factors, reliance on irrelevant factors, or decisions no reasonable authority could make; Diplock summarised review as Illegality, Procedural Irregularity and Irrationality while noting Proportionality as a future possibility. Indian jurisprudence applies Wednesbury principles for arbitrariness claims and reserves proportionality-based scrutiny where administrative action is challenged as discriminatory, reflecting a bifurcated approach to review depending on arbitrariness versus discrimination.