UK Withdrawal from the EU: Supremacy, Indirect Effect and Retained EU Law

The UK has left the EU and its withdrawal is managed by the European Union (Withdrawal) Act 2018 (EUWA). The EUWA domesticates a snapshot of EU law as 'retained EU law'. The supremacy principle is also domesticated, and benefits retained EU law in its interaction with prior (pre-IP completion day) domestic law. The domesticated supremacy principle's explicit confinement in this backward-facing way is designed to maintain continuity with the previous state of affairs, during EU membership, while also allowing for future regulatory divergence. In spite of this, however, this article argues that retained EU law has important ramifications vis-a-vis future UK Acts of Parliament through the forward-facing operation of the domesticated doctrine of indirect effect which the EUWA does not confine. The upshot is that the capacity to diverge in future from retained EU law is legally more constrained than might otherwise have been anticipated.