Boris Johnson’s Brexit strategy has been on trial ever since he became prime minister eight weeks ago, and on Tuesday his lawyers will defend it in the U.K.’s highest court.


Fresh from being lambasted by a fellow European leader after he opted out of a joint news conference Monday, Johnson will see his decision to suspend Parliament under scrutiny in the first of three days of hearings at the U.K.’s Supreme Court in London.


It’s a landmark hearing that not only threatens to undermine Johnson’s position as prime minister, but could also curtail the British executive’s longstanding power over when the legislature sits. Johnson could be forced to recall Parliament, giving opponents of a no-deal Brexit more room to try to thwart his “do or die” promise to leave the European Union with or without a divorce agreement on Oct. 31.


“People think that we’ve somehow stopped Parliament from scrutinizing Brexit, what absolute nonsense,” Johnson told the BBC in an interview broadcast Monday evening. “Parliament will be able to scrutinize the deal that I hope we will be able to do both before and after the European Council on Oct. 17.”


Johnson’s defiance came after a day of talks that suggested the two sides are no closer to reaching a Brexit agreement. European Commission President Jean-Claude Juncker complained the U.K. still hasn’t put forward any concrete proposals and Luxembourg’s Prime Minister Xavier Bettel criticized Johnson after he refused to appear alongside him at a press conference.


Hard Feelings
A noisy demonstration, in which protesters could be heard shouting “dirty liar” as music blared, prompted Johnson’s team to ask their hosts in Luxembourg to move the event indoors — but the request was denied and Johnson decided to leave the chaotic scene.


Bettel pressed on alone and, gesturing to the empty podium next to him, said it is time for Johnson to “stop speaking and act” to find a Brexit agreement. The U.K. prime minister and his Conservative Party are responsible for “the mess we’re in at the moment,” Bettel said.


“We need more than just words.”


“Our people need to know what is going to happen to them in six weeks’ time. They need clarity, they need stability and they need certainty,” Bettel told reporters. “You can’t hold their future hostage for party political gains.”


It was an ignominious end to a day that started with Johnson expressing hope for a deal. The U.K. is due to leave the EU at the end of October, and Johnson has said he is determined to leave the bloc by then, even if that means doing so with no divorce agreement in place.


Undeterred by Monday’s setbacks, Johnson said he is still “cautiously optimistic” agreement can be reached.


‘Take Some Work’
“The big picture is that the commission would like to do a deal,” Johnson told the BBC in an interview after the talks. The EU president is “highly intelligent” and wants a deal, the premier said. “But clearly it’s going to take some work.”


Juncker’s team said the U.K. has still not presented any proposals and it’s their “responsibility to come forward with legally operational solutions” to allow the free flow of goods between the Republic of Ireland, which is in the bloc, and Northern Ireland, which is in the U.K.


Johnson said he is offering alternative arrangements for the Irish border, the main sticking point in talks with the bloc, though refused to give specifics. “There’s a limit to how much the details benefit from publicity before we’ve actually done the deal,” he told the BBC.