On whether unconstitutional government action is unlawful. Lord Sumption points out that UK constitutional conventions are not enforceable in the courts, as Miller (UKSC) confirmed. 1/
True enough. But in the Brexit case there is also EU law. Art 50 states that a Member State (MS) may withdraw “in accordance with its constitutional requirements”. Note “requirements”, not “law”. Broad enough to capture UK conventions. 2/
Art 50 is law, not political practice or convention. The reference to constitutional requirements is not descriptive: legal provisions lay down norms. 3/
In Wightman the ECJ made ample reference to this phrase. It also put “democratic process” in the mix (paras 66 & 67). Defensible because democracy is an EU value. 4/
The ECJ also determined that a MS could revoke, again in accordance with constitutional requirements. Revocation ends the 50 process. Conclusion: the whole Art 50 process is governed by the MS’s constitutional requirements. 5/
So the UK is required, as a matter of EU law, to comply with its own constitutional requirements, including, I would argue, constitutional conventions. 6/
So EU law may have the effect of elevating conventions to binding law. Leavers may say: that’s exactly the sort of interference which necessitates leaving. 7/
Fair enough. But as long as the UK has not left it is bound by EU law. Not because the EU says so, but because Parliament has legislated to that effect: the ECA. 8/
Parliament could of course say otherwise, and override EU law - at least as a matter of UK law. But it has NOT done so. And the Government CANNOT at present override EU law, again as a matter of UK law. 9/
Conclusion: Lord Sumption may be right in general, but wrong in relation to Brexit when he says that constitutional conventions are not legally binding. END
