I read this in Abraham Lincoln's First Inaugural Address,
The fugitive-slave clause of the Constitution and the law for the suppression of the foreign slave trade are each as well enforced, perhaps, as any law can ever be in a community where the moral sense of the people imperfectly supports the law itself. The great body of the people abide by the dry legal obligation in both cases, and a few break over in each.
Is break over here related to the waves breaking over?
Oxford Advance Learner's Dictionary: 20. when waves break, they fall and are dissolved into foam, usually near land: The sea was breaking over the wrecked ship.
Do you think that break over here is just another figurative way to refer that a few people fail to fulfill their legal obligation?