Final answer:
The Fourteenth Amendment provided equal protection under the law post-Civil War and became pivotal for civil rights legislation, though the Supreme Court limited federal enforcement against private discrimination.
Step-by-step explanation:
After the Civil War, Congress amended the Constitution to guarantee equal protection under the law for all citizens under the Fourteenth Amendment. Congress would also use this amendment to pass additional civil rights laws. However, in the decades following the Civil War, the Supreme Court limited federal power and reinforced the notion of dual federalism.
The Fourteenth Amendment became a cornerstone for both civil rights and civil liberties legislation. It marked an expansion of federal authority, with its equal protection clause ensuring that states could not deny citizens their constitutional rights. Despite this, the Supreme Court, at times, undercut the scope of the Amendment by ruling that it did not authorize the federal government to act against private discrimination. As such, the journey towards genuine equality progressed unevenly and faced ongoing challenges.