word | | Constitution |
| December | Comoros | 23 December 2001 |
| December | Croatia | adopted on 22 December 1990; revised 2000, 2001 |
| December | Cyprus | 16 August 1960 note: from December 1963, the Turkish Cypriots no longer participated in the government; negotiations to create the basis for a new or revised constitution to govern the island and ... |
| December | Czech Republic | ratified 16 December 1992, effective 1 January 1993 |
| December | El Salvador | 20 December 1983 |
| December | Ethiopia | ratified 8 December 1994, effective 22 August 1995 |
| December | Grenada | 19 December 1973 |
| December | Guinea | 23 December 1990 (Loi Fundamentale) |
| December | Guinea-Bissau | 16 May 1984; amended 4 May 1991, 4 December 1991, 26 February 1993, 9 June 1993, and in 1996 |
| December | Iran | 2-3 December 1979; revised 1989 to expand powers of the presidency and eliminate the prime ministership |
| December | Ireland | adopted 1 July 1937 by plebiscite; effective 29 December 1937 |
| December | Italy | passed 11 December 1947, effective 1 January 1948; amended many times |
| December | Kenya | 12 December 1963; amended as a republic 1964; reissued with amendments 1979, 1982, 1986, 1988, 1991, 1992, 1997, 2001; note - a new draft constitution was defeated by popular referendum in 2005 |
| December | Korea, North | adopted 1948; completely revised 27 December 1972, revised again in April 1992, and September 1998 |
| December | Kyrgyzstan | ... a new constitution granting greater powers to the parliament and the government; amendments added on 30 December 2006 redistributed some power back to the president, but both November and December 2006 versions ... |
| December | Libya | ... the Libyan government, the Revolutionary Command Council replaced the existing constitution with the Constitutional Proclamation in December 1969; in March 1977, Libya adopted the Declaration of the Establishment of the People's ... |
| December | Monaco | 17 December 1962 |
| December | Montserrat | effective 19 December 1989 |
| December | Netherlands Antilles | 29 December 1954, Statute of the Realm of the Netherlands, as amended |
| December | Pakistan | 12 April 1973; suspended 5 July 1977, restored 30 December 1985; suspended 15 October 1999, restored in stages in 2002; amended 31 December 2003; suspended 3 November 2007; restored on 15 December ... |
| December | Peru | 29 December 1993 |
| December | Romania | 8 December 1991; revision effective 29 October 2003 |
| December | Russia | adopted 12 December 1993 |
| December | Slovenia | adopted 23 December 1991 |
| December | South Africa | 10 December 1996; this new constitution was certified by the Constitutional Court on 4 December 1996, was signed by then President MANDELA on 10 December 1996, and entered into effect on 4 ... |
| December | Spain | approved by legislature 31 October 1978; passed by referendum 6 December 1978, effective 29 December 1978 |
| December | Sudan | constitution implemented on 30 June 1998, partially suspended 12 December 1999 by President BASHIR; under the CPA, Interim National Constitution ratified 5 July 2005; Constitution of Southern Sudan signed December 2005 |
| December | Switzerland | revision of Constitution of 1874 approved by the Federal Parliament 18 December 1998, adopted by referendum 18 April 1999, officially entered into force 1 January 2000 |