The government has lost the High Court Article 50 case. The court has ruled that Article 50, the formal two-year process for leaving the EU, can’t be invoked without parliamentary approval. The government will appeal to the supreme court.
If parliament does get a vote on Article 50, I doubt that it would vote it down: the public voted for Brexit in a referendum, after all. But I suspect that parliament would demand far more detail of the government’s negotiating objectives than it is currently prepared to give.
The government’s defeat in this case is an embarrassment to Theresa May and the Attorney General Jeremy Wright, who appeared in court for the government. If the government were to lose again in the supreme court, the Royal prerogative would have been substantially weakened. Politically, it would have been more sensible for the government to have asked parliament months ago to approve the Prime Minister triggering Article 50 at a moment of her choosing.