Which case established the concept of liberty under substantive due process?

• A. Lochner v. New York (1905)
• B. Plessy v. Ferguson (1896)
• C. Brown v. Board of Education (1954)
• D. Citizens United v. FEC (2010)

Answer: (A)

Substantive due process protects certain fundamental liberties from government interference, not just fair procedure. Lochner v. New York is the classic case that shows this idea in action: the Court struck down a state law limiting bakers’ working hours, reasoning that the liberty to contract—the ability of individuals to negotiate and enter private work arrangements—is a protected aspect of liberty under the 14th Amendment. The decision framed government regulation of private economic conduct as potentially unconstitutional unless a legitimate public interest justifies it, thereby establishing liberty as a protected substantive right in this era.

The other cases focus on different constitutional questions. Plessy v. Ferguson centers on equal protection and racial segregation, not on substantive due process liberty. Brown v. Board of Education also hinges on equal protection and rejects “separate but equal” in education. Citizens United v. FEC deals with First Amendment protections for political speech and corporate spending, not with the liberty protected by due process.