Lucas v. Forty-Fourth General Assembly of Colorado
The Supreme Court struck down Colorado's state Senate apportionment plan, ruling that even though voters had overwhelmingly approved it in a 1962 referendum, it still gave rural areas far too much voting power compared with their population.
Decided the same day as Reynolds v. Sims, the ruling made clear that both chambers of a state legislature -- not just one -- must be apportioned based on population, and that a popular vote cannot excuse a plan that fails that standard.
How it got here: A three-judge federal district court in Colorado upheld the Senate apportionment as rational; the challengers appealed directly to the Supreme Court, which noted probable jurisdiction.
The Case in Depth
What happened
Voters, taxpayers, and residents of the Denver area sued Colorado officials, arguing that the state's legislative districts were so unequal in population that their votes counted for far less than those of rural residents. In 1962 Colorado voters had approved a constitutional amendment, Amendment No. 7, that apportioned the House by population but kept the Senate weighted toward less populous counties, based on geography, county lines, and other non-population factors.
The question before the Court
Could Colorado keep its 1962 voter-approved plan for the state Senate, which let counties with only about a third of the population elect a majority of senators?
The Court's answer
No — the Court ruled that Colorado's Senate apportionment plan was unconstitutional even though voters had approved it by a wide margin in a 1962 referendum. Because counties with only about a third of the state's population could elect a majority of the Senate, the plan failed the population-based standard the Court announced the same day in Reynolds v. Sims for both chambers of a state legislature.
The Court explained that a popular vote cannot excuse an apportionment scheme that violates the Equal Protection Clause, since an individual's right to an equally weighted vote is a constitutional right that cannot be taken away even by a majority of the electorate. The case was sent back to the lower court to work out how and when Colorado must adopt a new plan.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Colorado had to redraw its state Senate districts so that seats better reflect where people actually live, a change likely to shift political power toward the state's fast-growing Denver-area suburbs and cities. The ruling also warned other states that voter-approved apportionment plans are not immune from constitutional challenge, prompting redistricting fights nationwide.
What changes now
The case was sent back to the federal district court in Colorado to decide how quickly the new population-based standard must be implemented, including whether the 1964 elections could still proceed under the old plan given how close they were. The ruling required Colorado to eventually redraw its Senate districts, and it reinforced the broader nationwide requirement, set out in Reynolds v. Sims, that both chambers of state legislatures be apportioned by population.
What this does not decide
The Court left open exactly when and how Colorado had to implement a new Senate map, given the timing of the 1964 elections, and did not decide whether the Colorado House -- which the parties treated as already population-based -- fully complied with constitutional requirements.
Concurrences and dissents
Dissent — Justice Clark
Justice Clark argued Colorado's plan was rational given the state's mountainous, economically diverse regions and its history of using initiative and referendum to solve apportionment disputes. He objected to applying 'one person, one vote' rigidly to both legislative chambers, noting the Colorado House was already close to population equality, and warned the ruling would damage federal-state relations.
Dissent — Justice Stewart
“But legislators do not represent faceless numbers. They represent people, or, more accurately, a majority of the voters in their districts”Stewart's objection that population-only apportionment ignores the real interests legislators represent.
Justice Stewart argued the case had nothing to do with denying anyone's right to vote, and that the Equal Protection Clause only requires an apportionment plan to be rational and not systematically block majority rule. He detailed Colorado's mountainous geography and diverse regions as rational reasons for the Senate's design and would have upheld both the Colorado and New York plans.
How the Court got there
The legal reasoning, step by step
- The Court applied the rule announced that same day in Reynolds v. Sims: the Equal Protection Clause requires that seats in both houses of a bicameral state legislature -- not just one -- be apportioned substantially on a population basis, sometimes summarized as 'one person, one vote.'
- Although the Colorado House was apportioned close to population equality, the Court found the Senate apportionment let counties containing only 33.2% of the state's population elect a majority of the 39-member Senate, with population-variance ratios as high as 3.6-to-1 between the most and least populous districts.
- The Court rejected the argument that Colorado's Senate could be modeled on the two-senators-per-state structure of the United States Senate, reasoning that the federal analogy reflects a historical compromise among once-sovereign states that has no counterpart among counties within a single state.
- The Court held that a state's electorate approving an apportionment plan by referendum does not cure a constitutional defect, because individual voters' constitutional right to an equally weighted vote cannot be taken away even by a vote of the majority.
- Because the Senate apportionment fell far short of population-based representation and the two houses were not shown to be severable, the Court concluded the entire plan under Amendment No. 7 could not stand.
Doctrinal impact
Cases affected by this decision
Reaffirms Reynolds v. Sims
Applies the same-day ruling that both houses of a state legislature must be apportioned by population.
Reaffirms Baker v. Carr (369 U.S. 186)
Relies on it for the principle that malapportionment claims are a proper subject for federal courts to decide.