反する
はんする · hansuru · JLPT N1 · verb-suru
to oppose
反 = against, opposite + する = to do: 反する = to act against, contradict
反 is the kanji for against or opposite, as in 反対 (opposition). Add する and it becomes a verb: to go against a rule, a law, or a view.
反 — hand 又 under cliff 厂
Originally a pictograph of a hand (又) turning something over against a cliff or slope (厂), depicting the action of flipping or reversing. From this came the core meaning 'to turn over,' which extended to 'opposite,' 'contrary,' and 'rebel against.' The character is purely semantic, with no phonetic component.