The U.S. Supreme Court case Kirkpatrick v. Preisler (1968) centered around the issue of congressional redistricting in Missouri, and whether it violated Article 1, Section 2 of the Constitution which requires that representatives be chosen "by the People of the several States." The appellants argued that a population variance among districts was necessary to maintain political subdivisions within single districts and to avoid fragmenting areas with distinct economic, social or cultural interests. However, Preisler contended that these variances resulted in unequal representation for citizens across different districts. In its decision, the Supreme Court ruled against Kirkpatrick by stating there must be as close to equal population as possible in each district - any deviation from absolute equality must be justified by legitimate state objectives. The court held that maintaining political subdivision lines did not justify deviating from this principle since it could result in inequality among voters' influence over congressional elections. Therefore, Missouri's plan was deemed unconstitutional due to its failure to make a good-faith effort towards achieving precise mathematical equality among all its voting districts.

In the dissenting opinion for Kirkpatrick v. Preisler, Justice Harlan argued that the majority's requirement of absolute mathematical equality in population among congressional districts was unrealistic and unnecessary. He contended that such a strict standard would lead to excessive litigation and frequent redistricting, which could disrupt political stability and community representation. Moreover, he believed this approach ignored legitimate state interests like respecting municipal boundaries or natural geographic features when drawing district lines. In his view, small deviations from perfect population equality should be permissible if they are based on rational state policies rather than arbitrary discrimination or favoritism towards certain groups.