grandfather clause
noun /ˈɡrænfɑːðə(r) klɔːz/
/ˈɡrænfɑːðər klɔːz/
(North American English)- part of a new rule or law that does not apply to a particular group of people, allowing them to continue following the old rule or law
- There was a grandfather clause, limiting the new, higher building and plumbing standards to future construction.