the thirty-year rule
noun/ðə ˌθɜːti ˈjɪə ruːl/, /ðə ˌθɜːti ˈjɜː ruːl/
/ðə ˌθɜːrti ˈjɪr ruːl/
[singular]- a British government rule which prevented certain official documents from being made public until a period of thirty years had passed. It was replaced when the Freedom of Information Act was passed in 2005.
三十年规则：英国政府的一项规则，该规则禁止某些正式文件在三十年过去之前被公开。2005年通过《信息自由法》时，已将其替换。