To go against, disobey, or run counter to something (rules, orders, expectations, etc.).
彼は上司の命令に背いて独断で行動した。
He acted on his own against his boss's orders.
伝統に背くようなことをするつもりはない。
I don't intend to do anything that goes against tradition.
友情に背くような行為は許されない。
An action that betrays friendship is unforgivable.
法律に背く行為は厳しく罰せられる。
Acts that contravene the law are severely punished.