word | | Constitution |
| January | Czech Republic | ratified 16 December 1992, effective 1 January 1993; amended several times |
| January | Dominican Republic | 28 November 1966; amended 25 July 2002 and January 2010 |
| January | Equatorial Guinea | approved by national referendum 17 November 1991; amended January 1995 |
| January | Falkland Islands (Islas Malvinas) | 1 January 2009 |
| January | Gambia, The | approved by national referendum 8 August 1996; effective 16 January 1997 |
| January | Gibraltar | 5 June 2006; came into force 2 January 2007 |
| January | Guatemala | 31 May 1985, effective 14 January 1986; suspended 25 May 1993; reinstated 5 June 1993; amended November 1993 |
| January | Honduras | 11 January 1982, effective 20 January 1982; amended many times |
| January | Hungary | 25 April 2011, effective 1 January 2012 |
| January | India | 26 January 1950; amended many times |
| January | Italy | passed 11 December 1947, effective 1 January 1948; amended many times |
| January | Jordan | 1 January 1952; amended many times |
| January | Kazakhstan | first post-independence constitution adopted 28 January 1993; new constitution adopted by national referendum 30 August 1995 |
| January | Liberia | 6 January 1986 |
| January | Mali | adopted 12 January 1992 |
| January | Mongolia | 13 January 1992 |