because states can govern themselves
You need to be more specific. Tell us when and where.
Answereach State was interpreting laws for itself.
national court system, state court system and tribal court system.
(in the U.S.) that would be a reference to the Federal Court System (e.g.: US District Courts - US Courts of Appeal - The Supreme Court of the US - etc).
Yes, definitely. You do not need to be a US citizen to bring a lawsuit in the US court system.
Federal Court System
The US Supreme Court is the highest court in the US. Each state has its own Supreme Court, but the US Supreme Court is the end of the line.
The US Supreme Court is the center of the US justice system. The Supreme Court is the highest court in the country.
Federal Court System
Federal Court System
Federal Court System
Most cases reach the US Supreme Court via the US Court of Appeals Circuit Courts, which are part of the federal court system.