grandfather clause

/G R AE1 N D F AA0 DH ER0 K L AO1 Z/
noun
  1. 1

    A clause or section, especially in a law, granting exceptions for people or organisations who were affected by previous conditions.

    โ€œMany building codes include a grandfather clause exempting older buildings until some amount of remodeling occurs.โ€

Source: https://en.wiktionary.org/wiki/grandfather%20clause