London-Britain’s parliament on Monday finds itself in familiar territory -- arguing about Brexit -- with threats of rebellion and resignations over Prime Minister Boris Johnson’s controversial plan for a new law that will break his EU divorce treaty.

The House of Commons holds its first debate and vote over the bombshell new bill from late afternoon, despite a call from Brussels for it to be withdrawn by the end of the month.

The contentious legislation, unveiled last week, would override the divorce deal the UK struck with the EU last year in several key areas related to Northern Ireland.

It would see London unilaterally regulate UK trade and state aid within the British province, ignoring the EU treaty which gives Brussels a continuing say over Northern Ireland’s trading relationship.

If the law passes in the coming weeks, Brussels has warned it could scupper ongoing trade deal talks and threatened court action, leaving the prospects of an orderly Brexit in tatters.

Even some Brexiteer lawmakers were aghast that Britain would wilfully trash an international treaty, threatening the country’s reputation and potentially endangering Northern Ireland’s fragile peace.

Former prime ministers John Major and Tony Blair this weekend openly criticized the action, while David Cameron said Monday he had “misgivings” about the approach.

Meanwhile, Johnson’s pro-Brexit former attorney general Geoffrey Cox said it would be “unconscionable” to override an international treaty.

“I think it is wrong that the British government or our parliament should renege on an agreement on which we gave our solemn word,” he told Times Radio.