Therefore, one only needs to know certain social facts, eg whether certain wishes were expressed and the likelihood of harm for disobedience, habits of obedience etc. So the legal facts are determined by social facts alone with no relevance of moral facts. Moral facts have no role to determine sovereignty or legal obligations, that is the nature of law. So, for lawyer to figure out law only sociological date is enough, moral philosophy doesn't help.
All law is grounded in social facts, which are descriptive not normative. So, you only say someone is a sovereign because they are obeyed. So law becomes descriptive of the social state of the community. So making statement like someone is a sovereign does not illicit an ought from an is. For eg, if law says pay tax, we cannot infer that we ought to pay tax.
Austin's theories failures:.
1. It does not explain power-conferring rules. All rules need not impose obligations, there might be rules such as that relating to wills or contract which enable us to do something. These are power-conferring. They increase our positive freedom (ability to do). So, testator can ensure that property is distributed according to his desires. On the other hand, the duty imposing rules limit our negative freedom (Is to the extent that I am able to do something till nobody stops me). eg laws on homicide impose a duty not to kill which I might desire.
2. Equating nullity to sanction is not correct to explain power conferring rules as they just provide benefit. Moreover, they are not STANDING as duty imposing rules.
3. Duty imposed by rules are separate moral reasons to act for the good citizens, so only sanction cannot be the way in which law should be seen. Like rewarding good behavior or rewards. So laws cannot be mere commands. Commands as law only explain the bad citizen.
4. Power-conferring rules are explained by kelsen. He says that the power-conferring rule is really a part of a much larger rule that ultimately directs a legal official to impose a sanction.