The Supreme Court ruling means the Government will probably publish a Brexit bill tomorrow – and it's Labour's problem

This morning Labour said it would table an amendment designed to prevent the Government turning Britain into 'a bargain basement tax haven'. We look forward to the wording of that one

The lead claimant in the Article 50 case, Gina Miller, speaks to the media after she exits the Supreme Court (EPA)

Theresa May has lost her appeal to the Supreme Court, which ruled at 9.30 this morning that an Act of Parliament is required before the Government can trigger Article 50, to start the procedure for leaving the European Union. But the Prime Minister's embarrassment is limited. The bill is almost certain to go through Parliament in plenty of time for her deadline of the end of March, as I explained on Sunday.

There is a large majority in the House of Commons expected to vote in its favour. Not even the House of Lords, which is usually harder to control, is likely to obstruct it.

The judges also unanimously ruled that the Government is not required to consult the Scottish Parliament, Northern Ireland Assembly or Welsh Assembly before triggering Article 50, which removes the last plausible obstacle.

So the sting of defeat will hardly be noticed: the Court's ruling will now expose Labour's problems, as the battle will now be fought out over attempts to amend the bill as it goes through Parliament. In that struggle, Jeremy Corbyn and Keir Starmer, the shadow Brexit secretary, have to balance their claim that they “will not block Article 50” with their attempt to hold the Government to account.

​The Government will probably publish the bill tomorrow. Keir Starmer, the shadow Brexit secretary, has suggested that Labour will table an amendment to require a vote in Parliament on the Brexit deal in time to allow the Government to reopen negotiations. That could be an ingenious way of trying to position Labour as the party of soft Brexit rather than hard, but it is hard to explain to the public and, if the Government portrays it as an attempt to block Brexit, it can probably defeat it.

Starmer was honest about Labour's problems on ITV’s Peston on Sunday: “I’m not going to pretend that this isn’t difficult for the Labour Party. There are colleagues in the Parliamentary Labour Party who are very concerned, as am I, about the outcome of the referendum. We have two thirds of our MPs in heavily Leave areas, we have one third in heavily Remain areas. We need to talk to our colleagues and respect each other through this, but I’m not going to pretend there aren’t strong views, of course there are. It’s not a classic divide in the party, left/right or leadership/non-leadership. It’s a genuinely difficult issue that we need to handle with care and we will. But this is a party that campaigned to remain and is now accepting we've lost that and defining where we go from here.”

In effect, there is little Labour can do. Starmer will bring his legal skill to arguing for amendments that might be accepted in the House of Lords, such as guaranteeing the rights of EU citizens in Britain or for an early vote on the Brexit deal. This morning Labour said it would table an amendment designed to prevent the Government turning Britain into “a bargain basement tax haven”. We look forward to the wording of that one.

Procedurally, Starmer and Corbyn have a point in refusing to say how Labour MPs will be whipped. Starmer said: “That’s not yet been determined. We are talking to colleagues on this – we don’t know the outcome of the case and we haven’t seen the legislation.”

At one level, it makes sense to say that the party will wait to see the detail, but it means that Labour's policy is not clear to the voters outside Parliament. The big picture is that Theresa May is getting on with Brexit, and Labour basically agrees with her but would just like to make some points that no one can remember.