Thirty Year Rule

The Thirty Year Rule is the name given to the law in the United Kingdom, the Republic of Ireland and Australia, that states that the yearly Cabinet papers of a government will be released publically thirty years after they were created.

Usually this is on 1 January of a particular year. The only papers not released (or if they are contained in other papers 'blacked out') are those which are deemed to cause "damage to the country's image or foreign relations" if they were to be released.