Interveners make submissions in about half of the cases heard by the Supreme Court of Canada, but the motivations for and consequences of the practice are not clearly understood. Considered broadly, there are at least three functions that the practice of intervention might perform. The first possibility is that hearing from interveners might provide objectively useful information to the Court (i.e., interveners might promote the accuracy of the Court\u27s decision making). A second possibility is that the practice of intervention allows interveners to provide the best argument for certain partisan interests that judges might want to affiliate with. A third possibility is that interventions are allowed mainly (if not only) so that intervening parties feel they have had their voices heard by the Court and the greater public, including Parliament, regardless of the effect on the outcome of the appeal (i.e., the Court might be promoting the acceptability of its decisions by allowing for an outlet for expression). We examine empirically the role of interveners in all the cases decided by the Supreme Court of Canada from January 2000 to July 2009 and find statistical evidence that interveners matter
