The government has been defeated by 45 votes tonight. This loss doesn’t force a change in policy on Theresa May, but it is a significant blow to her negotiating strategy. She has been saying to the EU that with legally binding changes to the backstop, she could get the withdrawal agreement through parliament. The EU will argue that this result shows that even with changes to the backstop, May couldn’t get a deal through. They’ll therefore become more forceful in their attempt to urge her to come to an arrangement with Jeremy Corbyn on a customs union. The ERG have, ironically, made it less likely that May will get anything significant on the backstop and increased the chances of the UK ending up in a customs union with the EU.
No one from the government chose to respond to Jeremy Corbyn’s point of order straight after the vote. But by the end of this month, the Brexit dynamics could look very different. May’s negotiating position with the EU has been weakened tonight and it will be weakened still further if the Cooper amendment passes when it comes back. If it does, then MPs will face a choice between backing May’s deal and a lengthy extension to Article 50.