As of 2019, which nation's constitution has gone the longest without an amendment?

The current constitution of Japan (sometimes referred to as the 1947 Constitution or the Post-war Constitution) was enacted in May 1947. It replaced the earlier Meiji Constitution of 1889 following the Second World War and written primarily by American authors, but they took into account the earlier constitution while drafting the new document.

Human rights, democratic elections and equality of all are among some of the rights defined in the current constitution along with certain changes from the Meiji Constitution the abolition of peerage (or nobility) and the renunciation of war were included to prevent Japan from returning to their earlier militaristic behavior. Also the role of the Emperor is defined, but only as a ceremonial head of state, a stark contrast from the role defined by the Meiji Constitution.

As of 2019, two different draft amendments have been proposed, the one proposed in 2005, among other changes suggested, one involving rewording the constitution's preamble and modifying the constitution's wording concerning the renunciation of war. This draft amendment was met with limited public support. A second draft of the amendment was created in 2012, but as of November 2019 neither had been voted on to amend the constitution.

The most recent amendment to the U.S. Constitution, is the 27th, ratified in 1992. India’s constitution has had 103 amendment acts approved since its initial ratification in 1950. France’s most recent was ratified in 2008.