What are the adj and verb from contravention ?

See a translation

The verb form would be “contravene”

There isn’t really an adjective form. The most common way to use contravention in an adjective-like description is to say “[ ] is in contravention of [ ].” You could also use the past/present participle: contravened/contravening.

For example:

“A Texas law has been overturned after the Supreme Court found it *contravened* the Constitution.”

“A Texas law has been overturned after the Supreme Court determined it was *in contravention of* the Constitution.

“By using chemical weapons in Vietnam, the United States was *contravening* international law.”

“By using chemical weapons in Vietnam, the United States was *in contravention of* international law.”