yes
It depends on the "emperor" you are talking about. The emperor of Byzantium, or the Greek Eastern Empire, ruled a sophisticated state with many of the same powers and privileges as the ancient Roman emperors. The German emperors of the Latin West aspired to similar prestige, but ruled over a far more fractious polity and had to compete with powerful feudal barons for control of their realm.
maintains a federal system of government and representation.
majority opinion
McCulloch v. Maryland
The lower court cannot overturn the higher court's decision.
It depends on what you are referring to. An order of the civil court cannot overrule a finding of the criminal divisionany more than a finding of the criminal division can overturn a finding of the civil division. However a ruling of one may have direct effect on the actions of one of the principals in a case in the other branch.
a national economy and a strong federal government
In the US, a magistrate does not have the authority to overturn a trial court judges' ruling. If there was a trial and the Judge made an error, you can appeal within a certain amount of time. You would appeal to the state Appellate Court or Supreme Court, depending on how the state's courts are organized. However, not liking the trial judge's ruling is not grounds for appeal. There must be a legitimate legal basis, such as misapplication of the law. If you believe you have grounds for appeal, you should speak with your lawyer immediately.
yes it did
Although law professionals will tell you it is a separate system, it is not. The US Supreme court has ruled that these systems are separate in so much as they are bound by the State constitution, and the Federal constitutions as well as the rulings of the US Supreme Court. State courts cannot divert from a Federal Court ruling; if they do the US Federal Court system will overturn the ruling.
In the Federal court system, the district courts are the "lowest" courts. Cases usually start in district court and are decided there. The circuit courts are courts of appeal. That means that you can appeal a district court's ruling to the circuit court (and then to the Supreme Court, if you still don't like the ruling). In that sense, the circuit courts are "higher" than the district courts.
the ruling of state supreme courts are always the final judgment on a matter.