The right of the president to delay implementation of certain provisions is normally written into a law, to provide flexibility that Congress cannot offer.
[1] Such waivers enhance presidential control of domestic policy.
[1] There is also an extraordinary circumstances waiver in Section 502b of the Foreign Assistance Act.
[2] Ronald Reagan's administration used waivers in dealing with the Aid to Families with Dependent Children program in the 1980s.
President Bill Clinton also employed waivers to give state's flexibility in Welfare reform.