Question juridique clé
Whether the conviction for disturbing public order under Art. 26 RGP/Lausanne had a sufficient legal basis.
Solution extraite
The conviction was arbitrary because Art. 26 RGP/Lausanne prohibits conduct but itself contains no penal sanction; no other criminal basis was identified.
Motifs extraits
Under nulla poena sine lege, the lower courts could not uphold the fine on the sole basis of the communal prohibition. The cantonal judgment therefore lacked a sufficient legal foundation and had to be annulled.