Proportionality and Rationality: the Debate Goes On
British public lawyers live in interesting times. A long list of possible constitutional reforms has dominated their attention in recent times: devolution of powers, Scottish independence, human rights and the relationship with the European Court of Human Rights, membership of the European Union and, now, creation of a constitutional court. In the tumult, and especially considering the central role of the United Kingdom Supreme Court in these reforms, it is perhaps not surprising that the Court is interested in revisiting settled orthodoxy in areas of public law doctrine.
Regular readers will remember that, in Pham  UKSC 19, the Court accepted that proportionality has a role to play in the common law of judicial review and, moreover, that it now bears a significant family resemblance to rationality review. The stage has thus been set for the Court to rework the principles of substantive review, perhaps doing away with Wednesbury unreasonableness altogether in favour of a context-sensitive proportionality test.
Confronted, however, in Keyu v. Foreign Secretary  UKSC 69 with “the argument that the time has come to reconsider the basis on which the courts review decisions of the executive, and in particular that the traditional Wednesbury rationality basis for challenging executive decisions should be replaced by a more structured and principled challenge based on proportionality” (at para. 131), Lord Neuberger felt that this view “has implications which are profound in constitutional terms and very wide in applicable scope” (at para. 132). Wide enough that only a full panel could determine whether rationality and proportionality are finally to be merged: “if a proportionality challenge to the refusal to hold an inquiry would succeed, then it would be necessary to have this appeal (or at any rate this aspect of this appeal) re-argued before a panel of nine Justices” (at para. 132). Rylatt and Tomlinson have produced a very useful post on Keyu.
Most recently, in Youssef v. Foreign Secretary  UKSC 3 Lord Carnwath signalled his desire to revisit the relationship between rationality and proportionality, with a particular view to providing more useful doctrinal tools to lower courts:
In Keyu v Secretary of State for Foreign and Commonwealth Affairs  UKSC 69;  3 WLR 1665 (decided since the hearing in this appeal) this court had occasion to consider arguments, in the light of Kennedy and Pham, that this court should authorise a general move from the traditional judicial review tests to one of proportionality. Lord Neuberger (with the agreement of Lord Hughes) thought that the implications could be wide-ranging and “profound in constitutional terms”, and for that reason would require consideration by an enlarged court. There was no dissent from that view in the other judgments. This is a subject which continues to attract intense academic debate (see, for example, the illuminating collection of essays in The Scope and Intensity of Substantive Review: Traversing Taggart’s Rainbow ed Wilberg and Elliott, 2015). It is to be hoped that an opportunity can be found in the near future for an authoritative review in this court of the judicial and academic learning on the issue, including relevant comparative material from other common law jurisdictions. Such a review might aim for rather more structured guidance for the lower courts than such imprecise concepts as “anxious scrutiny” and “sliding scales” (at para. 55).
Properly defining rationality review so that it plays a constitutionally appropriate role by permitting judges to check rather than second-guess administrative decisions remains a pressing concern and I can attest to the utility of that excellent book (which you can order here) in considering issues relating to rationality, proportionality, reasonableness and deference.
In general, I do not think that rationality and proportionality review ought to be merged. While it is entirely true to say that both types of review are concerned with weight and balance and the calibration of the burden of justification, and that they may be animated by common values, important differences remain.
First, the burden of proof shifts explicitly in proportionality view. Once a violation of a protected interest is demonstrated, the burden is placed on the state to justify the interference. Meanwhile, in rationality review, when an applicant can point to indicia of unreasonableness, the burden does not shift in a formal sense but the respondent has a tactical interest in demonstrating that the decision deserves nonetheless to be upheld. Proportionality review requires a court to take several analytically distinct steps, but rationality review represents a holistic, one-step inquiry.
Second, courts ask different questions depending on whether they are engaged in rationality review or proportionality review. Despite the similarities between the two types of review, a court engaged in rationality review is not authorized by the relevant doctrinal rules to upbraid a decision-maker for failing to use a less restrictive alternative means of achieving its ends and may not second-guess the balance struck by the decision-maker between competing interests or substitute its own views solely on the basis that the court has a different view of the relative weights of the competing public and private interests.
Third, to the extent it is true that non-deferential rationality review and deferential proportionality review (see e.g. Youssef at para. 57) and their opposites resemble each other, this strikes me as a bug rather than a feature, liable to lead to insufficient protection of fundamental rights on the one hand and over-zealous scrutiny of decisions of lesser importance to individuals on the other.
It will be interesting to see what a nine-judge panel will ultimately do with the rationality/proportionality distinction.
This content has been updated on February 17, 2016 at 16:29.