The Roman Republic was certainly a thriving democracy by the standards of its time, but it should be noted that women, slaves, and many men were not allowed to vote.
The main causes of Shays' Rebellion all had to do with anger of tax and debt collection, which showed that the early United States had a very hard time exerting power over the individual states and the populations of these states.
Political upheaval in Germany caused people to seek freedom elsewhere wasn't the reason
All courts, except the US Supreme Court, are established by Congress.
