[1]The closure period was reduced from fifty to thirty years by an amending act of 1967, passed during Harold Wilson's government.
Significant changes were made to the rules as a consequence of the Freedom of Information Act 2000 (FOIA) (which came into full effect on 1 January 2005).
As a result of that change, releases now occur monthly, rather than annually, and include more recent events, rather than only those over thirty years old.
In the decision Babcock v AG Canada[5] the court explained the reason as:[6] The process of democratic governance works best when Cabinet members charged with government policy and decision-making are free to express themselves around the Cabinet table unreservedly.To preserve this rule of confidentiality, subsection 70(1) of the Privacy Act provides that the Act does not apply to confidences of the Queen's Privy Council for Canada.
[7] In May 2018, it was disclosed that the Supreme Court of Canada under Chief Justice Beverley McLachlin had placed a "50-year from the time they rule on a case" embargo on public access to files related to the deliberations of the judges.
The appointment in 1940 of Arnold Danforth Patrick Heeney[10] as Clerk and as first Secretary to the Cabinet changed the format of memory bank from biological to scriptural.
The more I learned about Cabinet practices, the more difficult it was for me to understand how such a regime could function at all.Order-in-Council PC 1940-1121 of March 25, 1940 ushered in a significant change in the documentation of government.
[7] In 2008, two years after Prime Minister Stephen Harper was elected, the tradition of annual voluntary releases of Cabinet Conclusions stopped.
NDP Member of Parliament (MP) Murray Rankin, a legal scholar, said at the time:[13] It's a question of political will.
[14] Israel adopted the British model of a thirty-year rule as the basis for reviewing and declassifying its foreign policy documents.
The principle of the law is that all material is to be released after thirty years, subject to limitations based on damage to state security, foreign policy or personal privacy.
In practice this means that declassification of documents are fixed at different periods based on type of material and date of production.