Law and ethics are interconnected because first, both are social sciences and second because both regulate people's behavior but from different perspectives.
The law is a variety of rules of conduct, created by the government with the aim of somehow force us to act in a defined way because these rules require us to obey. On the other hand, the ethic is a more flexible topic, it plays an important role in the way we act but it doesn't force anybody to act in a specific way.