In a boost to Brexit opponents, the European Union's top court has ruled that Britain can reverse its divorce from the bloc without consulting other member states.
The European Court of Justice saying that the British government can unilaterally revoke Article 50.
It comes on the eve of a crucial day in British parliament, when lawmakers will vote on Theresa May's Brexit deal - which faces fierce opposition.
Monday's (December 10) decision means that if Britain were to change its mind about Brexit, no EU approval would be required to halt the process.
And a revocation would not result in any penalties.
Many critics of Brexit see the ruling as a potential way out, via a second referendum.
The British prime minister's plan faces a backlash from lawmakers both for and against Brexit and many expect her deal to fail on Tuesday (December 11).
If May wins the withdrawal will likely proceed as agreed with Brussels last month.
A loss could result in a leadership challenge or perhaps a new referendum.
With the clock ticking ahead of the March 29 exit date, it is far from clear whether or how Britain could organize a "People's Vote" in time.
Many warn that it could stir unrest.
Opinion polls suggest that any new majority for staying in the EU is narrow.