Proportionality

Judicial review, as the Courts and Tribunals Judiciary explains, 'is a type of court proceeding in which a judge reviews the lawfulness of a decision or action made by a public body' — it is 'a challenge to the way in which a decision has been made, rather than the rights and wrongs of the conclusion reached'. Proportionality is one of the grounds on which such a challenge can be brought, and it was central to the Supreme Court's landmark decision in Bank Mellat v Her Majesty's Treasury (No 2) [2013] UKSC 39. There, the Treasury had directed that no UK financial institution could deal with a major Iranian bank, and the relevant statute required that 'the direction must be proportionate having regard to the risk to the national interest presented by' the risk in question. The Supreme Court's press summary records that 'the essential question' for the Court was whether the measure 'bore some rational and proportionate relationship to the statutory purpose' being pursued.

The Supreme Court held, by a majority, that singling out the one bank was 'arbitrary and irrational, and disproportionate to any contribution which it could rationally be expected to make' to the government's objective; the dissenting minority, by contrast, considered that 'the direction was rationally connected to the objective and was proportionate'. That divide illustrates how the proportionality test operates in practice — weighing the aim pursued, the rational connection between the measure and that aim, and the fairness of the balance struck against the individual affected. A former Attorney General's 2021 speech on judicial review trends noted the ongoing debate over how far this approach should extend beyond human rights cases, observing 'an increased readiness to import HRA-style proportionality into judicial review', with the Supreme Court 'entertaining the idea of proportionality as a general ground of judicial review' — a development some senior lawyers regard as controversial.