Brazil will put former president Jair Bolsonaro on trial next week on charges of attempting a coup after losing the 2022 election. If convicted, he could face decades in prison.

Many Brazilians — and many Americans watching from afar — see this moment as a triumph of democracy.

Brazil, which emerged from a brutal dictatorship just 40 years ago, will have accomplished something that the United States could not: bring a former president to trial on criminal charges that he attempted to cling to power after losing an election.

Yet the way Brazil did it has left the nation grappling with uncomfortable questions over the very democracy it sought to protect.

Those questions begin with Brazil’s Supreme Court.

Over the past six years, the court has given itself extraordinary new powers to confront what it viewed as an extraordinary threat posed by Mr. Bolsonaro and his attacks on institutions. For the first time, the court could launch and lead its own sprawling investigations, even when the victim was the court itself.