Testament spent half of the G20 weekend behind bars, so the hip-hop artist knows first-hand the power a simple letter can have.

It is has been nearly a month since the G20 rocked Toronto, but the events have not been forgotten. Accusations of detainee mistreatment, police brutality, and civil rights violations have been circulating since the summit weekend and continue to arise.

The former leader of Ontario’s NDP has a challenge for the G8 nations and...