In Santos & Others v SSEEU, a Divisional Court has been asked to make a declaration that the government cannot use the royal prerogative to trigger the UK's withdrawal from the EU under Article 50 of the Lisbon Treaty. Judgment is imminent. An appeal to the Supreme Court will be heard and adjudicated on by the end of December.
The litigation highlights the tension between two fundamental principles: the Crown's power in respect of international treaties versus that of parliamentary sovereignty.
Royal Prerogative
The Claimants argued that by creating enforceable rights, the ECA 1972 prevents the UK from withdrawing from the EU without parliamentary approval; the prerogative power to conduct foreign relations without parliamentary authority is only possible because it is irrelevant to the existence of rights in national law. The Government argued that the prerogative could only be extinguished if Parliament had specifically legislated to preclude its use (which it has not).
The court suggested that the logic of the Government's stance is that the Crown could negotiate the UK's withdrawal from the EU without even holding a referendum. Considering a parallel case, the High Court of Northern Ireland held that this is a matter of high policy, unsuitable for judicial review, and that the prerogative power has not been displaced.
Rights conferred by Parliament
The Claimants argued that triggering Article 50 will lead, unlawfully, to the inevitable loss of rights conferred by Parliament. The Government's position was that (i) the Claimants have overstated the effect on individual rights (in reply, the Claimants argued that they only need to establish that one such right will be lost), (ii) a substantial number of rights (such as voting in European elections) only take effect as a matter of domestic law (an argument which left the court 'slightly baffled'), and (iii) Parliament will soon have a central role in passing the Great Repeal Bill.
The Government also rejected arguments by the Claimants to the effect that without further intervention by Parliament, the devolution settlements all rest on continued membership of the EU, arguing that those settlements assume, but do not rest on, membership of the EU.
Reversibility
The parties proceeded on the assumption that notification under Article 50 cannot be withdrawn. If it could, this would destroy the Claimant's case that the notification would have immediate, irreversible consequences adverse to individual rights. Although reversibility would be a trump for the government, it would be politically unpalatable to suggest that Brexit may not mean Brexit. Though unlikely, the court could refer the question to the CJEU (which would lead to an outcry from Leavers and delay the present proceedings by several months).
Initial views
Although generally wary of straying into highly 'political' areas such as this, the court subjected the lawyers for the government to sustained and searching questions, particularly on the question of rights conferred by the ECA. Though finely balanced, there is a very real possibility that the claim may succeed, forcing the government to reconsider elements of its Brexit strategy.