Schedule B - Constitution Act, 1982 (79)
PART I - Canadian charter of rights and freedoms
Legal Rights
14. A party or witness in any proceedings who does not understand or speak the language in which the proceedings are conducted or who is deaf has the right to the assistance of an interpreter.
Fair trial standards
Victims' rights
Witnesses' rights
Rights during investigation - access to interpreter and translation if questioned in other language
Rights during trial - interpretation and translation
EDIT.