During the 2010 G20 Toronto summit, Des Rosiers uncovered a provision invoked by the provincial government which greatly expanded police powers near a security fence on the perimeter of the summit's location. She brought this issue to the attention of the Canadian press and ensured that CCLA volunteers monitored the Toronto police for civil liberties violations during the conference. She also helped to discourage the practice of "carding", where police stop people who are not suspected of any criminal activity, ask for their identification and record that information for later review.