Final answer:
The prominent issue that the Supreme Court faced from the Civil War to the beginning of the New Deal was labor and economic regulation.
Step-by-step explanation:
The prominent issue that the Supreme Court faced from the Civil War to the beginning of the New Deal was Labor and economic regulation. During this period, there were several significant cases related to labor rights and economic regulation that came before the Supreme Court, including cases involving worker protections, labor unions, and industrial regulation.