At around 11 p.m. on Mar. 13, a Gatineau, Que., police officer phoned Radio-Canada reporter Antoine Trépanier to inform him he was under arrest for doing his job and that he should report to the police station.

The story has caused a public stir because of what Mr. Trépanier does for a living, but the scandal lies in the actions of the police: Arrest now, check the facts after.

Mr. Trépanier was working on a story about Yvonne Dubé, a local Big Brothers and Big Sisters official who allegedly omitted to disclose to the charity’s board she was once caught practising law without a licence.

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He says he phoned her twice seeking an interview and left messages, and sent her one e-mail. They also spoke once by phone. She lodged a complaint for criminal harassment.

When Mr. Trépanier arrived at the police station, he signed a promise to appear in court at a later date. Here’s what didn’t happen: He wasn’t asked to provide a statement or meet investigators. No one asked a judge for a warrant for his arrest, or permission to check phone or e-mail records. And no one formally charged him with a crime.

Gatineau Police Chief Mario Harel insisted on Friday that his department did its job, saying that “with all the movements involving women who lodge complaints” it is incumbent on police to believe women who experience harassment and fear for their safety.

That’s true. Many police services in Canada are slow to deal with such complaints (and also sexual-assault complaints).

But believing complainants and taking allegations seriously does not equate to reflexively arresting people over the phone. It involves doing one’s job, thoroughly, expeditiously and with due care.

Mr. Trépanier wasn’t harassing anyone. Journalists have a Supreme Court-mandated duty to offer story subjects like Ms. Dubé every opportunity to respond to accusations against them.

The Gatineau police made a serious error in this case. And they have only made it worse by trying to blame their actions on the #MeToo movement.