Law deals with who should win a given conflict. As ethics is the area of philosophy dealing with guides to action, i.e. what one should do, law therefore must be a subset of ethics as it tells us who should direct the use of something.
Law deals with conflicts. Conflicts can only occur between multiple individuals, meaning law specifically is a subset of inter-personal ethics.
As law is a subset of ethics, all legal claims are moral claims, but not all moral claims may be legal claims.1