20 Years in a Federal Prison would be a deterrent to any intelligent person thereby assuring you that no intelligent would ever even consider doing this for any reason. You'll still have leftists doing it though since liberalism and intelligence can not live together in the same brain.
The concept of banishment as criminal punishment has always been legal in the United States. While the Constitution does not specifically discuss banishment, banishment is still legal under the Constitution as long as due process is followed.
