OH look, another Vow. Speaking at an event in London, Labour's Scottish branch manager Anas Sarwar is to announce what he proudly bills as an "alternative to independence". Sarwar's alternative is a "legal duty of co-operation" between Holyrood and Westminster. 

It's shades of writing the Sewel Convention into law all over again. As long as what passes for the British constitution is founded upon the principle of the absolute sovereignty of the Westminster Parliament and the doctrine that no Westminster Parliament may bind its successor, Sarwar's legal duty of co-operation is worth as much as the promise that the Sewel Convention, stating that no Westminster government would ever alter the powers of the Scottish Parliament without the express consent of Holyrood, would be written into the Scotland Act and made a legal obligation.

As we all know, the second that the Conservative government of Theresa May found this to be an inconvenience, they went to the UK Supreme Court which ruled that the provision had no legal force.  For good measure, the British Government also redefined what “consent” means. If Holyrood said “yes” it would be taken as consent, if Holyrood refused to engage with the question it would be taken as consent, and if Holyrood said “no” that would be taken as consent too. 

So if Sarwar and the Labour Party are touting this legal obligation for Westminster and Holyrood to co-operate as their great idea to offer an attractive and plausible alternative to independence, it is incumbent upon them to explain how future Westminster governments are going to be bound by it. 

Obviously this legal obligation to co-operate is only going to become law if there is a Labour government. That's a big if by itself, but given the typical pattern of English general elections over the past 100 years, as sure as night follows day, that Labour government will inevitably be followed by a Conservative one.

So given Scotland's experience with the Sewel Convention being written into law, and then seeing it being overruled, and a Supreme Court judgment being sought to rule that no government could be bound by it, we are entitled to know: what guarantees can Sarwar give that a future Conservative government will not repeal his legal obligation to co-operate, sideline it, or render it meaningless by redefining "co-operation" so that Holyrood is legally bound to co-operate with Westminster but Westminster is not obliged to co-operate with Holyrood?

The short answer is that he cannot. Since it is a fundamental tenet of the Westminster system that Parliament cannot bind its successors, there is absolutely nothing that can guarantee that a future British Government will not repeal it.  

And all this is if Westminster honours the commitment in full in the first place and does not do as it did with the promise to enshrine the Sewel Convention in law and insert the weasel word “normally” into the phrasing of the law in order to give itself a convenient escape clause.

Westminster could very well decide that its end of the “co-operation” bargain consists of instructing Holyrood what to do, and then Anas Sarwar would go on BBC Scotland to announce that his promise had been fulfilled, and a fawning presenter would just smile and nod.

The basic problem here for Anas Sarwar and the Labour Party is that we have heard all this from them before. While what Labour sees as the “threat” of another referendum is on the horizon, Scotland gets promises and commitments about devolution that we are assured will be enshrined in law. But the second a No vote is produced and the prospect of independence recedes, Labour and the other Westminster parties go back to their contemptuous business as usual.

Scotland has seen how they behaved and how their promises turned out to be hollow, so Labour does not get any benefit of any doubt this time round. The Westminster parties deceived Scotland before, the onus is on them to prove that this time it will be different. Given that Labour is as much in thrall to the fetishisation of Westminster parliamentary sovereignty as the Tories are, that is proof that they cannot give.

This piece is an extract from today’s REAL Scottish Politics newsletter, which is emailed out at 7pm every weekday with a round-up of the day's top stories and exclusive analysis from the Wee Ginger Dug.

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