Justin Trudeau, the leader of the Liberal Party, was sworn in as prime minister of Canada on Wednesday morning, ending nearly a decade of Conservative rule.<br />Mr. Johnston, as Queen Elizabeth II's representative, fulfills most of the duties of head of state here, including administering the oath of office to government ministers.<br />Though the swearing-in took place inside Rideau Hall before a small invited audience, Mr. Trudeau broke with recent tradition by inviting the public onto the grounds of the residence, where two giant television screens allowed them to watch the proceedings.<br />The mood of the enthusiastic crowd on the tree-lined lawns contrasted markedly with the somber public gatherings in Ottawa on Oct. 22, on the anniversary of an attack by an Islamic extremist who killed a ceremonial guard near the Parliament building in 2014 .
