Executive also agrees that, where any part of the agreements set forth in this Agreement or in its application is held to be invalid or unenforceable, then the remainder of the Covenant or Covenants shall be endowed with all its force and effect, without regard to any invalid or unenforceable parts thereof. However, a party wishing to invoke this principle must demonstrate that the provision is objectively impossible and not only difficult, painful or economically painful. The North American Free Trade Agreement (NAFTA), signed by Prime Minister Brian Mulroney, Mexican President Carlos Salinas and U.S. President George H.W. Bush, entered into force on January 1, 1994. NAFTA has created economic growth and a rising standard of living for the citizens of the three member states.