The Supreme Court judgment on the UK Government's plans to ignore the constitution is a good read.
The Government's case was that "the 2015 [referendum] Act was enacted on the assumption that the result of the referendum would be decisive."
Er, that's it.
That was plainly not the case, merely outrageous political positioning by the Brexiteers.
The Supreme Court judgment explains why the referendum could not be decisive (at paras 91-92) and why the 2015 referendum Act was flawed (at 118-119).
Basically, if the Tories had wanted the Brexit referendum to be decisive (i.e. for Brexit to proceed immediately on a 'Yes' result), they would need to have included in the 2015 Act the detailed changes to the law to permit that to happen. The 1975 EC referendum Act, for example, had no such details and was therefore properly presented by ministers at the time as being only advisory. They knew that more complex legislation had to follow if the UK were to join. Indeed, so did Cameron's government. The Supreme Court found that in 2011 the government had agreed with the proposition that "Under the UK’s [constitution] Parliament must be responsible for deciding... action in response to a referendum..." (see para 125).
Clearly, the Brexiteers concluded they had little chance of being able to frame the necessary detailed legislation to leave the EU, and just wanted to snatch a quick result. So they decided to copy the original 'simple' EC referendum Act of 1975 and claim (however wrongly) that the referendum on this occasion would be decisive. Others clouded that issue by 'promising' to abide by the outcome, even though the referendum result could only have political significance, rather than any legal status. They then drove around in their big red bus, blithely misleading people about the alleged benefits, and dismissing expert analysis of the major problems associated with leaving the EU. No doubt they did this in part to secure their own electoral future(s), but you can tell from where they are now that the lead Brexiteers were not roundly congratulated by their Tory colleagues for their conduct and its consequences. As the Supreme Court noted (at para 124):
"...the referendum of 2016 did not change the law in a way which would allow ministers to withdraw the United Kingdom from the European Union without legislation... unless and until acted on by Parliament, its force is political rather than legal."
The question now is whether Parliament should perpetuate the scam.
There is much hand-wringing about the 'will of the people' (well, 52% of them, anyway) but little apparent appetite among MPs for recognising that the 48% were not fully informed and calling a halt to plans to trigger Article 50 unless and until the government can explain the detail. MPs are best at ducking issues, not addressing them.
But the fact that Brexit continues to divide the country should tell them all they need to know: when in doubt, don't do it. They might vote it through, but no one will thank them for the consequences.