State party Valid from Valid until Spain Sri Lanka Sweden Switzerland 25 11 23 18 25 January 1993 Indefinitely Indefinitely 18 September 1997 United Kingdom of Great Britain and northern Ireland United States of America Zimbabwe 20 May 1976 8 September 1992 20 August 1991 C. January 1985 June 1980 March 1976 September 1992 Indefinitely Indefinitely Indefinitely States parties to the Optional Protocol (66) State party Date of receipt of the instrument of ratification, accession or succession b_/ Date of entry into force Algeria Angola Argentina Australia Austria 12 10 8 25 10 September 1989 a/ January 1992 a/ August 1986 a/ September 1991 a/ December 1987 12 10 8 25 10 December 1990 April 1992 November 1986 December 1991 March 1988 Barbados Benin Bolivia Bulgaria Cameroon 5 12 12 26 27 January 1973 a/ March 1992 a/ August 1982 a/ March 1992 a/ June 1984 a/ 23 12 12 26 27 March 1976 June 1992 November 1982 June 1992 September 1984 Canada Central African Republic Chile Colombia Congo 19 8 28 29 5 May 1976 a/ May 1981 a/ May 1992 a/ October 1969 October 1983 a/ 19 8 28 23 5 August 1976 August 1981 August 1992 March 1976 January 1984 Costa Rica Cyprus Czechoslovakia Democratic People's Republic of Korea 29 November 1968 15 April 1992 12 March 1991 a/ 23 March 1976 15 July 1992 12 June 1991 10 April 1990 &/ 10 July 1990 Denmark Dominican Republic Ecuador Equatorial Guinea Estonia 6 4 6 25 21 23 4 23 25 21 January 1972 January 1978 a/ March 1969 September 1987 a/ October 1991 a/ -170- March 1976 April 1978 March 1976 December 1987 January 1992