Migrants from Somalia cross into Canada illegally from the United States by walking down a train track into the town of Emerson, Man., on Feb.26, 2017. A federal judge has struck down a key agreement on refugees between Canada and the United States. In a ruling today, Federal Court Justice Ann Marie McDonald says elements of the law underpinning the Safe Third Country Agreement violate constitutional guarantees of life, liberty and security.THE CANADIAN PRESS/John Woods