The United States v. Fields case ended up on a federal death sentence imposed on Fields for commitig a federal capital offense.
This sentence was made largely on the basis of the opinion of a psychiatrist who stated that he could predict Fields would be a risk to society in the future.
The problem here is that the psychiatrist issued this crucial testimony without doing any testing or offering any objective empirical data whatsoever.
To this day, there's still much debate involving how a Court can determine risk to society or future violence from an individual, in a safe and reliable manner that reaches necessary standards for a case of such magnitude assessing death penalty.
Hope this helps!
The correct answer to this open question is the following.
What is the role of the U.S. Constitution in limiting government power in the criminal justice system?
The Constitution of the United States clearly states that there is a system of checks and balances in which none of the three branches of government has more power over the other two, This includes the judicial branch that relies on a Supre Court. And here comes the central point of this answer. The federal courts are subjected to the US Congress and this legislative branch has the power to enact criminal laws such as treason, bootlegging, or counterfeiting.
Does it really limit the behavior of those in the criminal justice system?
It could be better understood in that it serves as a counterbalance to the criminal justice system, in the same way, that the Supreme Court checks the legislative branch by declaring some laws unconstitutional.
Because it was a very large melting pot of culture, religion, and location.