It’s against the law to drive through a red light.
She’s studying law to become a lawyer.
“That is no excuse, ” replied Mr. Brownlow. “[…]; for the law supposes that your wife acts under your direction.” — “If the law supposes that, ” said Mr. Bumble, […], “the law is a ass - a idiot. — (Charles Dickens, Oliver Twist , chap. 51)