Final answer:
The prosecutor is largely responsible for seeking death penalty sentences in a court of law, with the jury ultimately deciding upon the penalty in the federal system and some state systems.
Step-by-step explanation:
In the American court system, it is the responsibility of the prosecutor to seek a death penalty sentence if it is believed that a case merits such a punishment. The prosecutor represents the government and will argue during the trial that based on the evidence and gravity of the crime, the defendant should be subject to capital punishment. Once the case is presented, in the federal system and some states, the jury then decides whether or not the defendant should be condemned to death or given life imprisonment if the prosecution is pursuing the death penalty. The overall trial process is overseen by a judge who ensures fairness and adherence to legal procedure, but it is not the judge's role to seek the death penalty.