Final answer:
The 1876 Cruikshank decision allowed lynching to continue by ruling that the federal government could not prosecute individuals for offenses like assault and murder, which limited federal enforcement of civil rights and enabled a climate of racial violence and impunity.
Step-by-step explanation:
The Supreme Court enabled lynching through the 1876 Cruikshank decision which significantly limited federal enforcement of civil rights protections. The decision arose from the Colfax Massacre and established that the Fourteenth and Fifteenth Amendments protected individuals from actions by the state and not by other individuals. As a result, the federal government was deemed to have no right to prosecute individuals for ordinary crimes like assault and murder, even in the context of racially motivated violence like lynching. This ruling effectively closed the door to federal intervention, emboldening those who would later commit acts of racial violence secure in the knowledge that federal prosecution was unlikely.
Further complicating matters, the Enforcement Acts designed to protect African Americans and to combat the Ku Klux Klan's reign of terror encountered obstacles in their application and enforcement. With convictions rare and lynchings frequent, a climate of impunity fostered an environment where extrajudicial killings could continue without legal consequence. Despite the efforts of Black leaders like Ida Wells and the introduction of over two hundred federal anti-lynching bills, the fierce opposition of white Southern Democrats prevented these from becoming law.