Gerry Bowler is a Canadian historian and a senior fellow of the Frontier Centre for Public Policy. Ever since that fateful day 2,000 years ago when Judas Iscariot sold out his friend for 30 pieces of silver, switching sides and joining the enemy camp has had a bad name.Indeed, the names of those who do so, like Benedict Arnold during the American Revolution and Vidkun Quisling in Nazi-occupied Norway, have become shorthand for treachery.What then is one to make of the recent defection of four opposition members of Parliament to the ruling Liberal Party?Hundreds of their predecessors have done the same over the years. Since 1867, 307 MPs have changed allegiance in the midst of their term of office. The first to do so seems to have been Stewart Campbell of Nova Scotia, who had been elected as an opponent of Confederation in 1867 but abandoned that cause a year later and joined Sir John A. Macdonald’s Conservative-Liberal coalition. For his actions, he was pelted with eggs back in Antigonish.This sort of defection is common enough to have influenced the design of the House of Commons in Britain and its empire.Centuries ago, when parliamentary democracy was developing in England, it was common for supporters of the King to sit on one side of the House and opponents of the ruling clique to sit across from them, separated by a space wider than two swords’ lengths, a distance meant to discourage heated debate from becoming violent. (That distance is still in evidence today in legislative chambers around the Commonwealth, including Ottawa.) Thus, when one shifted loyalties, the term became “crossing the floor.”.When the British House of Commons was destroyed by German bombing during the Second World War, Winston Churchill insisted that it be rebuilt in the traditional fashion rather than adopting the semicircular design common in European legislatures. He argued that the opposing benches reinforced clear government-opposition confrontation and made “crossing the floor” a momentous act.Why do Canadian MPs shift parties midstream?Some floor-crossing emerges out of a genuine principle. MPs have found themselves in a party with which they no longer agree. Others move out of resentment at being snubbed for a lucrative cabinet or parliamentary secretary post, losing a leadership race, or wanting to be on the winning side of the next election.After struggling with their consciences and winning, defectors will utter phrases such as “wanting to be at the decision table” or “building a better future” for their constituency.The ambitious seem to far outnumber the principled.By looking at the direction of defections, we can see that jumps to the governing party are far more common than to the Opposition..Of the 77 MPs who changed parties since 1968, only four left the government to join its opponents. Two left the Progressive Conservatives to establish the Bloc Québécois. One Liberal defected to the Conservatives, and a single Conservative moved to sit with the Liberals.What is the fate of such turncoats? Taking Canadian history as a whole, more of those who have changed parties win re-election than not, but there has been a shift in those numbers in the modern era. Political scientists believe that for a century after Confederation, Canadian voters tended to vote more for individuals than parties, making it not unreasonable for a popular MP to be chosen again.In recent decades, however, voters seem to have been motivated more by the choice of party than by individuals. That would account for the number of unremarkable or undistinguished men and women who are elected as MPs (the sort of politician whom Pierre Trudeau derided as “nobodies” when they were “50 yards away from the House”).Since 1968, however, that shift toward party-based voting has not boded as well for floor-crossers as in earlier times. Half of those who ran again in the next election were defeated, but that figure hides an interesting fact. Of those who joined the government, two-thirds were successful in winning another term.Therefore, the Gang of Four who recently joined the Liberals have reason to be optimistic about their futures..Should such defectors be forced to seek immediate re-election on crossing the floor?Most Canadians think so.In a recent poll, 41% of respondents said that an MP who crossed the floor should resign and run in a byelection under their new party banner. Twenty-two percent think the MP should serve out his term as an Independent, and only 26% believe that an MP should be allowed to immediately join another party and continue serving.Those arguing the need for an immediate byelection may recall that, until 1931, it was compulsory for a Canadian MP who had been appointed to cabinet to go back to his constituency and seek re-election. The rationale was that accepting a cabinet post was considered an “office of profit under the Crown,” which legally created a potential conflict of interest.If re-election for floor-crossers were mandated, the purely ambitious Judases might have second thoughts, and voters would be more confident that their choice of representative was respected.Gerry Bowler is a Canadian historian and a senior fellow of the Frontier Centre for Public Policy.