His book Friends of the Court: The Privileging of Interest Group Litigants in Canada (State University of New York Press, 2002), a revision of his doctoral dissertation, discussed the treatment of interest groups seeking leave to intervene before the Supreme Court of Canada.
Friends posited that the court had come to favor a preferred set of interest groups, and explored the legal theory by which this had come about.
In 2003, he took leave from Western to become assistant to the chief of staff in the office of the federal leader of the opposition, first under Harper when he led the Canadian Alliance, then under Grant Hill's interim parliamentary leadership in 2004.
When Harper became leader of the successor Conservative Party of Canada, he appointed Brodie its executive director.
His book At the Centre of Government (McGill-Queen's University Press, 2018) is based in part on his experiences with Harper.