Which is why they continue to demur from ruling on it. The Court seems to be waiting until they can see whether or not the EU accept the letter as being 'fit for the purpose' that the Benn Act requires of it. And it looks like they will.
Doesn't stop it appearing that Johnson is being rather childish in respect of the letter. Here's what I have been asked to provide - but nah-ney-nah I haven't signed it...
Well if it makes him and his team feel clever then they can feel clever. But to me it most certainly isn't Prime Ministerial or in any way dignified, rather disrespectful to the EU in fact - goodness knows what they think of him - a bit desperate and pathetic probably - and rather supports the accusation that he'll do anything that he thinks deflects responsibility from himself to others.
It's all rather sad but perhaps not surprising behaviour.
As sad as it is I don't blame Johnson for doing what he did. He is a puppet PM with no majority, the strings being pulled by other parties and those in his own party that don't agree with him. The obvious course is a GE but the opposition knows it won't win, so continue to just jerk the strings.
Maybe the other side should agree to an election. It will be fought, predominantly, around Brexit and would be that second referendum that so many are asking for.