Grandfather Clause

The General Agreement on Tariffs and Trade (GATT) provision that allows the
original contracting parties to exempt from general GATT obligations
mandatory domestic legislation which is inconsistent with GATT provisions,
but which existed before the GATT was signed. Newer members may also
"grandfather" domestic legislation if that is agreed to in negotiating the
terms of accession. (U.S. legislation also provides for "grandfather
clauses.")