A system where only the national government is sovereign is called

Dictatorship

Explanation:

Sovereign means that an institution could rule over the rest of the people with complete authority. This can be found in a Dictatorship.

Under the dictatorships, every words that spoken by high government officials are absolute. The people have no right to question them unless they wanted to expose themselves to potential punishments.

The national government government will control every aspects of citizens life. This include things such as the type of jobs that they can pursue, the types of religion/ideologies should be taught to the people, the type of news that can be broadcasted in televisions, etc.

answer; obscene;