When our founders wrote our Constitution, two common legal systems were in use by Western countries. The English common law system was chosen by the founders for the United States. The system they rejected was called Roman law.
The difference was English common law said anyone charged with a crime is innocent until guilt is proven to a jury of peers. Roman law said being charged is proof of guilt until the charged proved their innocence. Roman law has been adopted by socialist governments.
The closed-door impeachment process Democrats used was an “illegal, un-American, unconstitutional” Roman law fraud.