Nullum crimen, nulla poena sine praevia lege poenali is a basic maxim in continental European legal thinking, authored by Paul Johann Anselm Ritter von Feuerbach as part of the Bavarian Code in 1813. This maxim states that there can be no crime committed, and no punishment meted out, without a violation of penal law as it existed at the time. This basic legal principle has been incorporated into international criminal law. It thus prohibits the creation of ex post facto laws.

However, we have to be careful about what we mean by 'penal law' -- penal law is taken to include the prohibitions of international criminal law, not only those of domestic law. Thus prosecutions have been possible of such individuals as Nazi war criminals and officials of the German Democratic Republic responsible for the Berlin Wall, even though their deeds may have been allowed or even ordered by domestic law. Also, courts when dealing with such cases will tend to look to the letter of the law at the time, even in regimes where the law as it was written was generally disregarded in practice by its own authors.

This principle is enshrined in several national constitutions, and a number of international instruments. See e.g. European Convention on Human Rights, article 7(1); Rome Statute of the International Criminal Court, articles 22 and 23 (see [1])

For discussion of these issues, see Streletz, Kessler, and Krenz v. Germany (European Court of Human Rights), and K.H.-W. v. Germany (European Court of Human Rights).

The maxim itself is sometimes rendered:

• nullum delictum, nulla poena sine praevia lege poenali
• nullum crimen, nulla poena sine praevia lege poenali
• nullum crimen, nulla poena sine lege praevia

or abbreviated to:

• nulla poena sine lege
• nullum crimen, nulla poena sine lege
• nullum crimen sine lege

See also

• Nulla poena sine lege