Afoul is almost never used alone. The phrase you need is run afoul of (American English; people also say fall afoul of, and in British English you may see run foul of, without the a-). If you run afoul of the law, you do something the law does not allow, and trouble follows. You can also run afoul of a school rule, a boss, or what a group believes is right — so it is not only about crime. The word feels a little old and serious. In daily talk, get in trouble with is more common. Foul here is the “wrong / tangled” foul, not the sports foul. The picture is probably of things getting tangled, like ropes on a ship, and then of a person getting tangled with rules.