Which case established that the redistricting of state legislative boundaries must adhere to population equality?

The case that established that the redistricting of state legislative boundaries must adhere to population equality is Baker v. Carr. This landmark Supreme Court decision emphasized the principle of "one person, one vote," which is central to the concept of political representation in a democracy. The Court determined that legislative districts must be drawn in a way that ensures roughly equal populations in each district, thereby providing equal weight to each citizen's vote during elections. Prior to this ruling, many states had significant discrepancies in district populations, which led to unequal representation.

Baker v. Carr set a precedent that allowed individuals to challenge the legitimacy of districting plans, thereby enabling federal courts to intervene in state legislative redistricting matters. This decision reinforced the broader implications of the Equal Protection Clause of the Fourteenth Amendment, asserting that electoral district malapportionment is justiciable under this constitutional guarantee.

In contrast, the other cases mentioned do not pertain to the principles of districting and population equality. For example, Citizens United v. FEC focuses on campaign finance and free speech, while Bush v. Gore relates to the presidential election process and recounting of votes. McConnell v. FEC deals with the regulation of campaign finance and the constitutionality of certain