CONSTITUTION OF BOTSWANA
CHAPTER II - Protection of Fundamental Rights and Freedoms of the Individual (ss 3-19)
10. Provisions to secure protection of law
(8) No person shall be convicted of a criminal offence unless that offence is defined and the penalty therefor is prescribed in a written law:
Provided that nothing in this subsection shall prevent a court of record from punishing any person for contempt of itself notwithstanding that the act or omission constituting the contempt is not defined in a written law and the penalty therefor is not so prescribed.
Nullum crimen sine lege
Nulla poena sine lege
EDIT.