It was adopted by the National Assembly of Poland on 2 April 1997, approved by a national referendum on 25 May 1997, and came into effect on 17 October 1997.
Foi adoptada pola Asemblea Nacional de Polonia o 2 de abril de 1997, aprobada por un referendo nacional o 25 de maio de 1997, e entrou en vigor o 17 de outubro de 1997.