That's according to a ruling handed down by the High Court in London.
However, the government will appeal.
Prime Minister Theresa May says she will activate Article 50 by the end of March 2017, at which point formal negotiations on Brexit can begin.
UK correspondent Olly Barratt says this ruling has provided her with an unwanted obstacle.
IN: "The government…
OUT: …significantly."
DUR: 40 seconds
http://www.fsnradionews.com/feeds/1103brexit-ob-generic.mp3