By Adam Payne

Suzanne Plunkett/Reuters

Lord Chief Justice for England and Wales John Thomas (C) gestures in the Prince’s Chamber before the State Opening of Parliament in the House of Lords, at the Palace of Westminster in London Britain May 27, 2015. REUTERS/Suzanne Plunkett.

One of the most important constitutional cases in Britain’s history came to an end on Tuesday and the case for forcing the government to ask parliament’s permission to trigger Article 50 is a lot stronger than first imagined.

Since Thursday, three of the UK’s most senior judges heard arguments regarding whether prime minister Theresa May is legally obliged to pass an act of parliament before invoking Article 50.

The case, which Business Insider attended, was held at the Royal Courts of Justice in central London.

A long line of people snaked around the court building hours before the doors opened each morning, a level of interest which had not been seen for any case at the court before, a security guard told us. And protesters gathered outside the court while the case was being heard.

Back To The High Court This Morning For Day Two Of Our Constitutional Challenge Against The Government! #Article50

— Charlie Mullins OBE (@PimlicoPlumbers) October 17, 2016

That is because the case is a blockbuster. The final verdict will have a huge say in how and when Britain leaves the European Union. It will set a historic constitutional precedent.

After three days of intense discussion and interrogation, it was clear that the case being made against the UK government was much more compelling than most commentators and media had initially believed.

Lord Pannick QC, who was representing lead claimant Gina Miller, who BI interviewed in August, argued strongly that triggering Article 50 will mean statutory rights enjoyed by Brits as EU citizens — like the right to vote to in EU elections and refer a legal dispute to the European Court of Justice — will be destroyed in an instant.

The government, Pannick added, cannot use prerogative power to do this. He said UK law demands MPs to give Theresa May their permission before the prime minister triggers Article 50.

The consequence of notification is to destroy rights and take the preservation of rights out of parliament’s hands. This cannot be done

“There is no dispute, that once notification is given, there is a direct causal link betwee