> So, David Cameron could have designed the Brexit referendum to require a double majority of national voters and constitutent countries
I'm not sure he could have designed it to "require" anything, since after all it was a non-binding referendum, with which the government was free to do whatever it chose, and it's not clear that there is any basis for a binding referendum.
The decision after the fact to treat the referendum as if it were a binding, simple-majority-rule, measure, OTOH, is ceetainly questionable.
The decision after the fact to treat the referendum as if it were a binding, simple-majority-rule, measure, OTOH, is ceetainly questionable.
There were plenty of questionable things about the referendum, but I really don't think this was one of them. If you look at Hansard during the debates on the enabling legislation, one MP after another spoke in terms of giving the people the final say, or words clearly to that effect. If you look at the official booklet, sent to every household in the UK by the government at taxpayers' expense, it too contained wording that clearly implied the people would decide.
Personally I'm of the view that we need more direct democracy to fix our political systems rather than less, and I see little democratic legitimacy in arguments about Parliamentary sovereignty given the alternatives available to us today. So for me, whether or not I agree with the result, as a matter of principle I would have preferred the referendum to be absolutely legally binding anyway. But even if our most senior lawyers held that it was not, it seems quite clear that even before the vote the expectation both of Parliament and of the general public was that the referendum result should decide the matter.
The referendum legislation could have been drafted to contain a clause specifying in which situations it would have been "deemed to have passed". That clause could have contained the requirement for a double majority. Of course, being a non-binding referendum, such a clause could not have had any direct legal effect, but it would have been politically near-impossible to disregard. There is no logical contradiction between the idea of a referendum being legally non-binding and the idea of a referendum with a higher threshold for passing than "50%+1 nationally".
I'm not sure he could have designed it to "require" anything, since after all it was a non-binding referendum, with which the government was free to do whatever it chose, and it's not clear that there is any basis for a binding referendum.
The decision after the fact to treat the referendum as if it were a binding, simple-majority-rule, measure, OTOH, is ceetainly questionable.