con ‧ tra ‧ ven ‧ tion /ˌkɒntrəˈvenʃ ə n $ ˌkɑːn-/ BrE AmE noun
[uncountable and countable] when someone does something that is not allowed by a law or rule SYN violation
contravention of
Sending the troops was a contravention of the treaty.
in contravention of something (=in a way not allowed by a rule or law)
Several of the girls were wearing trousers, in contravention of the school rules on dress.