In thwarting a Brexit vote, lawmakers seek extra insurance against an abrupt departure from the European Union without a deal to shape future relations.
LONDON — For the ever-wary lawmakers who sit behind Prime Minister Boris Johnson in Britain’s House of Commons, one insurance policy on his rollicking leadership was not enough. So on Saturday, they took out another.
So distrustful have lawmakers become of their famously brazen prime minister — and of one another — that they voted on Saturday not to vote at all on Mr. Johnson’s much-heralded Brexit plan.
They had already passed a law to prevent the prime minister from abruptly pulling Britain out of the European Union without a deal managing future relations. But on Saturday they went further, saying that even the deal that Mr. Johnson had struck with the European Union was not a strong enough guarantee that Britain would not leave without one.
So they bought themselves a second layer of protection against such an outcome, forcing the government to ask for an extension and putting off the fateful decision on his deal until a no-deal departure was a more remote possibility.
In an era of fractious disagreements and high-stakes political gridlock in Britain, the decision to add extra insurance was more evidence of the hollowing out of confidence among lawmakers that their colleagues would abide by the courtly traditions and effete codes of conduct that once dominated the chamber.
“The arteries of Parliament are built on this sort of trust,” said Alan Wager, a research associate at The U.K. in a Changing Europe, a research institute.
“It’s founded on the good-chap theory of government, the idea that people will abide by norms and culture, and that’s where the breakdown is,” he said. “The fury and frustration in the House of Commons is because of the magnitude of the decisions and the tightness of the votes.”
Lawmakers said they had good reason to distrust Mr. Johnson.
In an effort to quash dissenting voices in Parliament and push his Brexit plan through, Mr. Johnson had already asked Queen Elizabeth II to suspend Parliament, a move the Supreme Court deemed unlawful. And in striking a deal this past week with the European Union on the terms of Britain’s departure, he broke a major promise of his about how he would treat trade in Northern Ireland.
As a result of their misgivings, lawmakers have repeatedly tied the government’s hands, going so far as to pre-write a letter to the European Union for the prime minister because they did not trust him to follow the chamber’s edicts. A pregnant Labour lawmaker even delayed giving birth to appear for a pivotal vote in a wheelchair, suspicious that her pro-Brexit adversaries would not honor the usual system of taking medical absences into account.
The delay to Saturday’s vote on Mr. Johnson’s new Brexit agreement came in the form of an amendment put forward by Oliver Letwin, a former Conservative lawmaker exiled from the party by Mr. Johnson. Mr. Letwin supported the deal, as did some other lawmakers who voted to force a postponement.
But Mr. Letwin and other lawmakers said they worried that it was a prelude to parliamentary chicanery by Mr. Johnson or his hard-line Conservative allies that would result in a catastrophic no-deal Brexit within weeks. His amendment delays final approval of the agreement until after Parliament passes the detailed legislation to enact it.
That guarded against British lawmakers’ approving Mr. Johnson’s deal in principle on Saturday, but then holding up the detailed legislation that would follow.
Despite the earlier law seeking to avert a no-deal departure, that sequence of events would have left Parliament powerless to stop a no-deal Brexit on Oct. 31.
Among the most important backers of delaying a decision were a group of lawmakers furious at Mr. Johnson over the deal. In order to avoid imposing a border on the island of Ireland, his agreement creates a regulatory and customs border of sorts between Britain and Northern Ireland.
That angered unionist lawmakers for whom close ties between those two regions are sacrosanct — all the more so because Mr. Johnson had earlier promised not to put any distance between the two.
Philip Hammond, a Conservative ex-chancellor, on Saturday compared Mr. Johnson’s deal to getting on a bus without knowing where it was going.
“Before I decide whether to jump on the prime minister’s bus,” he said, “I’d like to be just a little clearer about the destination.”
For a prime minister who thought he was on the verge of a breakthrough, the voting on Saturday amounted to a remarkable comedown. But some of the anger at the prime minister was fueled by the very tactics that his allies credit for getting him a new deal.
In the delicate last stage of trying to win approval, though, Mr. Johnson is finding that those fights have depleted a precious reserve of good will among his colleagues, analysts said.
“It rebounds on him,” Mr. Wager said. “He got the agreement because he was willing to break the rules. And now people’s knowledge of the rules is coming back to haunt him.”
He added, “The attempts to second-guess the intentions of the government and safeguard against specific actions of the government — this is a new element, and it’s because of a lack of trust.”
Not all the lawmakers who voted to disrupt Mr. Johnson’s Brexit plan on Saturday did it because of worries about procedural trickery. Some opposition lawmakers simply want to delay and ultimately reverse Brexit, and depriving Mr. Johnson of a fast, up-or-down vote helped their cause.
But even lawmakers who were considering supporting Mr. Johnson’s agreement said they worried they were being “duped,” as Mr. Hammond put it, into voting for a no-deal Brexit in disguise. They fear that after clinching approval, Mr. Johnson will run down the clock on a transition period and fail to secure a free-trade agreement with the European Union, allowing Britain to effectively leave the bloc without a deal protecting trading ties and other arrangements in December 2020.
John Baron, a Brexiteer in the hard-line European Research Group, said as much in a televised interview. He described how senior government ministers had given him “clear assurance” that Britain would effectively leave the European Union on no-deal terms at the end of 2020 if trade talks failed.
Rob Ford, a professor of politics at the University of Manchester, said, “The European Research Group keep saying the silent bit out loud.”