Which Supreme Court case established that state legislative districts must be drawn with roughly equal populations, leading to the 'one man, one vote' principle?

• A. Marbury v. Madison (1803)
• B. Baker v. Carr (1962)
• C. Citizens United v. FEC (2010)
• D. Brown v. Board of Education (1954)

Answer: (B)

The idea being tested is how the Supreme Court handles drawing legislative districts so that each vote has roughly equal weight. Baker v. Carr is the best answer because it established that cases about how districts are drawn are justiciable in federal courts—it opened the door for courts to intervene in malapportionment issues. This set the stage for the later, more explicit requirement that districts be constructed with roughly equal populations, ultimately leading to the one man, one vote principle.

Marbury v. Madison is about judicial review, Citizens United addresses campaign finance, and Brown v. Board of Education concerns school desegregation. They don't establish the framework for enforcing equal-population districts in state legislatures.