In MacDougall v. Green, the U.S Supreme Court ruled in favor of Illinois' election laws that required third-party candidates to gather a certain number of signatures from at least 50 counties before they could be listed on the ballot. The plaintiffs, members of the Progressive Party, argued this law violated their Fourteenth Amendment rights as it was easier for established parties to meet these requirements than new or minority parties. However, the court held that states have broad powers to determine their own political processes and structures including regulating how political parties appear on ballots. It also noted that while there may be disparities in population among different counties which makes gathering signatures more difficult in some areas than others; such differences do not necessarily violate equal protection principles under the Constitution since they are based on legitimate state interests like preventing electoral confusion and ensuring statewide support for candidates.

In the dissenting opinion for MacDougall v. Green, Justice Wiley Rutledge argued that the Illinois statute requiring a new political party to obtain petition signatures from at least 200 voters in each of at least 50 counties was unconstitutional. He believed it violated the Equal Protection Clause of the Fourteenth Amendment by discriminating against citizens living in highly populated urban areas where obtaining such signatures would be more difficult due to population density and diversity. Furthermore, he contended that this law effectively suppressed minority parties' ability to participate in elections, thereby undermining democratic principles. The majority's decision upholding this law, according to Justice Rutledge, failed to protect fundamental rights and liberties enshrined within the Constitution.