British Prime Minister Boris Johnson will meet with the rest of the leaders of the European Union in a summit in Brussels on Oct. 17 in what will probably be the last chance to reach an exit agreement before Brexit day on Oct. 31. Then on Oct. 19, the British Parliament will hold an extraordinary session to assess the outcome of the summit and to decide what to do next.
A last-minute agreement between London and Brussels is still possible, especially if the United Kingdom agrees to keep at least Northern Ireland in a customs arrangement with the European Union, which would avoid the need for a hard border on the island. But if no agreement is reached, Johnson will be under legal pressure to ask the European Union for an extension. If he does not, the British opposition could oust him through a no-confidence motion. Considering the current fragmentation of...