Final answer:
Homer Plessy's civil disobedience challenged segregation laws through the Plessy v. Ferguson case, leading to the upheld 'separate but equal' doctrine and instigating Jim Crow laws.
Step-by-step explanation:
In 1892, Homer Plessy initiated a planned act of civil disobedience against the Louisiana Railway Accommodations Act of 1890. Plessy, who was one-eighth Black, deliberately sat in a Whites-only train car and declared his racial background, leading to his arrest. This act of defiance was in partnership with the Comité des Citoyens (Committee of Citizens), aiming to challenge the law and the separate but equal doctrine. The resulting case, Plessy v. Ferguson, ultimately led to the U.S. Supreme Court upholding the segregation law, reinforcing the legality of 'separate but equal' accommodations and paving the way for the establishment of Jim Crow laws that institutionalized racial segregation until their eventual dismantlement during the Civil Rights Movement.