The supreme court’s ruling on article 50 on Tuesday was perhaps inevitable, after a high court ruling that the government should not have spent time (82 days) and taxpayers’ money (a still unspecified amount) challenging. But it was a significant moment in the Brexit process, and showed that the prime minister should never have attempted to sideline parliament.

Thus ends the uncertainty over the article 50 process. Now comes the substance.

Last week the prime minister made a speech setting out her Brexit objectives. She confirmed that she intends to take Britain out of single market membership and parts of the customs union, and seek to negotiate a comprehensive free trade agreement in their place. This is a tall order, with high risks. And the higher the risk, the greater the scrutiny should be. If the prime minister fails, it will be families, working people and communities across the country who will pay the price.

There can be no question of implementing May's threat to turn the UK into a tax haven economy

That is why, when the government introduces its article 50 legislation, Labour intends to table amendments to hold the prime minister to account throughout the Brexit process.

First, the government should publish a document – ideally a white paper – formally setting out its negotiating objectives so that the progress and outcome of the article 50 negotiations can be tested against them.

Second, the government should report back to parliament regularly during the negotiations so that progress can be known and checked. I accept, of course, that this must not undermine the negotiations, and any Labour amendment will reflect this.

Third, MPs should be given a meaningful vote on the final agreement – that means a vote cannot take place with just days to go before the end of the process, and must be held before any vote in the EU parliament.

These amendments – and others Labour is considering – would give meaning to the parliamentary process and ensure we have a robust system in place to ensure accountability throughout the negotiations. The government should welcome this and seize the opportunity to strengthen the oversight and scrutiny of the Brexit process. The best outcome will be one that is challenged and tested at every opportunity.

Having fought in the courts to deny MPs a say on article 50, the government would be quite wrong to now introduce legislation that is near-impossible to amend or debate. That would be completely against the spirit of the ruling.

These amendments also hint at a wider, but often ignored point: the triggering of article 50 is merely the start of the process for leaving the EU; it is not the end. Much more important is the nature and extent of any new agreement between the UK and the EU. That agreement will define our relationship with the EU, and we have choices about what that should look like.

Labour’s guiding principles are that:

• Jobs and the economy must come first. That is why we have insisted throughout on the importance of tariff- and impediment-free access to the single market – which is crucial for our manufacturing sector – and a deal that works for services as well as goods

• All rights enjoyed because of our EU membership over the past 43 years should be preserved in full and without qualification. Those include all workplace rights, and environmental, consumer and human rights

• Any new agreement should promote the continuation of collaborative working between the UK and the EU in areas such as science, technology, medicine, crime prevention and counter-terrorism, among other things

• There can be no question of implementing the prime minister’s threat to destroy our social model and turn the UK into a tax-haven economy if she fails in negotiations. That would completely undermine social protection and workplace rights.

To help achieve these ends, Labour will insist that the prime minister cannot unilaterally change domestic law in the course of Brexit negotiations. Whether this is through the proposed “great repeal bill” or other legislation, every change to domestic law as a result of Brexit must be through primary legislation, voted on in parliament. That will give MPs on all sides of the house the chance to campaign and make the case for the kind of Brexit deal they believe Britain needs.

That is upholding parliamentary sovereignty; triggering article 50 is just the start of the process. The battle ahead will be long and difficult.