The Department of Justice has the mandate to support the dual roles of the Minister of Justice and the Attorney General of Canada.

Under Canada's federal system, the administration of justice is an area of shared jurisdiction between the federal government and the provinces and territories. The Department supports the Minister of Justice in her responsibilities for 49 statutes and areas of federal law by ensuring a bilingual and bijural national legal framework principally within the following domains: criminal justice (including youth criminal justice), family justice, access to justice, Aboriginal justice, public law and private international law.

The Department also supports the Attorney General as the chief law officer of the Crown, both in terms of the ongoing operations of government and of the development of new policies, programs and services for Canadians. The Department provides legal advice to the Government and federal government departments and agencies, represents the Crown in civil litigation and before administrative tribunals, drafts legislation and responds to the legal needs of federal departments and agencies.