Huge Ruling: Prime Minister Can't Trigger the Brexit

As Britain's lord chief justice puts it, "the most fundamental rule of the UK constitution is that parliament is sovereign." The Guardian's translation: It's a "setback" for Prime Minister Theresa May. The country's high court on Thursday ruled that only parliament has the power to formally begin the Brexit process. More:

• The ruling means Article 50 can't be triggered without parliamentary approval. The Wall Street Journal does see it as "theoretically" possible that lawmakers could slow or halt the process, though it notes May's Conservative Party is the largest party in Parliament.

• The Guardian explains the rub with Article 50: It declares that each EU member may exit "in accordance with its own constitutional requirements." It's not defined beyond that, which opened the door for both sides to make their argument.
• So how to go about making one's case? Sky News reports that during the case "there were colorful references to Henry VIII, to the 1689 Bill of Rights, to the 1610 Case of Proclamations, and to the rights of lobster fisherman in Newfoundland after a Treaty with France in 1892."
• May had previously announced her plan to trigger Brexit by March 31, setting the stage for a summer 2019 exit, with the AP reporting she was relying on a power called the royal prerogative that lets the government withdraw from international treaties. Those who opposed such a move said that the people will sacrifice some of their rights (like free movement within the bloc) due to the exit, and as such, parliament's blessing is necessary.
• The government says it will appeal, per the BBC; the supreme court has made room in its schedule to hear the case in early December.

(More Brexit stories.)