In the centralised EU system, though, EU law imposes a common system on all Member States which have to work together as part of a whole. When a Regulation is "done in Brussels" and enters into force, it applies immediately to all 28 Member States, having direct effect without any intervention from national legislatures.
The law that applies in one Member State simultaneously applies in all others. It is system-wide law aimed with the aim of integrating the Member States into a single administrative body.
That was never the case in Commonwealth and Empire. Law was made for each of the territories. Thus, law made for Australia would not apply to India, nor to South Africa - there was no Empire law, as such, a single body of law made in London which would apply to the UK and then equally and simultaneously to the rest of Empire.
Thus, when it comes to the Great Repeal Bill, the Government is gong to have great difficulty in separating out the functional aspects of the law and those dealing with the establishment of the EU systems, which are worked into the law. It will need to keep the one and remove the other. And that's not as easy as it looks.
We've seen this with fishing
, where the core regulation
does not just regulate fishermen but also sets up the Common Fisheries Policy, empowering the European Commission to perform certain functions, and imposing the duty of co-operation on (multiple) Member States.
Had the fisheries policy been written on the lines of Indian colonial legislation, it would have been framed by a "governor" based in London but appointed by Brussels, yet would have applied solely to UK waters. That we could have adopted, pro-temp, until we had something better. But Regulation 1380/2013, as it stands, is unusable without very substantial amendment.
More recently, we've seen exactly the same type of problem with the Lift Directive
. This is also dual-purpose regulation Not only does it legislate for lift safety, it is one of the "New Legislative Framework" package which sets up a Brussels-based system of control over a wide range of products. As such, once again, it empowers the Commission and places cooperative duties on Member States.
We've been though many other examples, from chemical regulation
to Air Traffic Management
, and there are many more to come. But even now, it is evident that Government has vastly under-estimated the complexities of repatriation, and is not at all geared up to dealing with the problem.
The original proposal to adopt the Efta/EEA option as an interim solution to a staged process was intended to avoid problems such as these, but we have seen Davis, May and the others, blunder into a "plane crash Brexit", eyes wide shut.
They've committed themselves to something that is virtually impossible to achieve in the time, and don't even understand the scale of the mess they've landed themselves in.