The following chart indicates provisions concerning non-retroactivity in criminal law adopted by the various nations of the world. It also covers the related doctrine of mercy (lex mitior) where a later law mitigates a penalty. All UN member states are included in this chart, plus Chechnya, the Republic of China (Taiwan), Kosovo, Turkish Republic of Northern Cyprus, the Palestinian Authority, Sahrawi Arab Democratic Republic (Western Sahara), Somaliland, and the State of Vatican City (the Holy See). These entities each make claims to be a state (Chechnya, Kosovo, N. Cyprus, W. Sahara, Somaliland, Vatican), to be the legitimate government of a state (Rep. of China), or to have the right to become a state (Palestine). Non–UN members are indicated with “x” on the chart.

1. C = Constitutional provision (including constitutional provisions incorporating human rights treaties with legality provisions, and constitutional provisions that may not be clear on their face but have been authoritatively interpreted by the court of highest jurisdiction in the nation) (Cols. 2-4).

2. S = Statutory provision (with no clear constitutional provision). Also included here would be case law not tied to a constitutional provision (Cols. 2-4). Note that in a few countries, it is difficult to distinguish between constitutional and statutory provisions.

3. T = Treaty provision (with no clear constitutional provision, and no statutory provision found) (Cols. 2-4, relevant treaties listed in Col. 5 whether or not there are constitutional provisions).