The convention of cabinet secrecy protects the views and opinions of ministers and the process of decision-making from disclosure to political opponents.
(d’Ombrain 2004, 333-335)
Secrecy of cabinet proceedings is one of the cornerstones of the Westminster system of government. The secrecy is protected by convention, the common law and - in differing degrees - statute law in the principal countries with Westminster systems, notably the United Kingdom, Canada and Australia.
Cabinet secrecy has undergone a notable evolution in Canada over the past fifty years. Two developments are of particular significance: first, matters to which protection is afforded has significantly expanded; second, the courts in Canada have been removed from any role in determining the validity of claims of cabinet secrecy at the federal level, and there is no duty in the courts or elsewhere to weigh the competing claims of public and private interests in the disclosure of cabinet secrets. The second of these developments is clearly the consequence of Parliament’s decisions in the 1970s and 1980s to use its authority to replace the common law functions of the courts in respect of cabinet secrecy. The expansion of the protection is also at least in part the consequence of the decision to legislate the scope of cabinet secrecy beginning in 1970.
Cabinet secrecy is widely assumed to be akin to executive privilege, shielding all that is internal to the cabinet. The cabinet secrecy convention does not protect the substantive secrets of the cabinet; rather, it protects the processes whereby ministers arrive at decisions. That is all it protects. The common law and related statutory provisions may provide greater protection, but to the extent that is so, they exceed the scope of the secrecy convention. The convention of cabinet secrecy protects the views and opinions of ministers and the process of decision-making from disclosure to political opponents, who could exploit such information to undermine the unity of the government and hence its ability to maintain the confidence of the House of Commons.
d’Ombrain, Nicholas. 2004. “Cabinet Secrecy.” Canadian Public Administration 47 (3): 332-359.