The High Court today handed down its decision in Miller v Secretary of State for Exiting the European Union. As has now been widely reported, the High Court found that the Government could not use its prerogative powers to trigger a notification under Article 50 of the Lisbon Treaty to withdraw from the European Union. Notification under Article 50 would require the approval of Parliament.
The Court (after affirming that the case was justiciable) accepted, at para  of its judgment, that it was “common ground” that Article 50 was irrevocable, since Government lawyers had not contested this point. This starting point made it easier for the Court to find, at paras – of its judgment, that rights would be affected by notification, including rights of workers (such as under the EU Working Time Directive), and rights enjoyed by British citizens and companies in relation to activities in other EU Member States. The Court also discussed, in dealing with legal background, the various presumptions governing how legislation is to be interpreted, and the link between these presumptions and constitutional precepts. Constitutional precepts relevant in this case include parliamentary sovereignty and the notion that prerogative powers cannot be used to alter domestic law.
The Court’s decision that prerogative powers could not be used for notification was reached through the prism of parliamentary intention: an interesting approach for the Court to take, which arguably helps to shield the Court from inevitable accusations of judicial activism. The Court asked whether Parliament intended, through the European Communities Act 1972 (which it considered to be a ‘constitutional statute’: –), to allow the prerogative to issue an Article 50 notification. In deciding that Parliament did not intend for prerogative powers to have this effect, the Court appeared to rely on two key principles:
- The principle that prerogative powers cannot be used to remove rights. The Court expressed this at para  as “the basic position” that “the Crown cannot through the use of its prerogative powers increase or diminish or dispense with the rights of individuals or companies conferred by common law or statute or change domestic law in any way without the intervention of Parliament.” This had been a core argument of David Pannick QC in oral submissions.
- The principle that where a statute ‘covers the field’, prerogative cannot be relied upon. Margit Cohn has called this ‘the rule of residuality’ (in (2005) 25 OJLS 97). The Court seemed to conclude that the ECA had covered the field, as noted at para (8) where it said: “It is not compatible with this degree of Parliamentary control – listing the main ‘Treaties’ in the ECA 1972 itself and providing for a high degree of Parliamentary control by way of approval by resolution of both Houses before an ancillary treaty qualifies as a ‘Treaty’ for the purposes of the Act – that Parliament at the same time intended that the Crown should be able to change domestic law by the simple means of using its prerogative power …”
Both principles could have been specified more precisely, and their application to the European Communities Act might have been made clearer. That said, the Court had limited time to deliver its judgment.
From a human rights perspective, it would seem especially important that the scope of the principle that prerogative powers cannot be used to remove rights be given further attention. What does it mean for the prerogative to “diminish” rights? The Miller case involved a clear removal of rights through treaty withdrawal. But in other cases should a proportionality test be used, or is interference with a right sufficient? These questions await further academic and judicial consideration.