Derek T. Muller, Ballot Access (forthcoming, Oxford Handbook of American Election Law):

Voters use ballots to choose their preferred candidates or to express support or opposition to ballot initiatives and referenda. There are many and diverse rules for how these people or items appear on the ballot in the first place—who can obtain “ballot access.” Once states began printing ballots in the late nineteenth century, they began to develop standards for which candidates, political parties, or ballot measures could appear on the ballot. States may require prospective candidates to circulate petitions and secure a number of signatures from voters to demonstrate support before their names could appear on the ballot. States set deadlines for candidates to circulate those petitions or to file for candidacy. Or states may limit the candidates who may appear on the general election ballot to those who meet a threshold level of votes in an earlier round of voting.

In the middle of the twentieth century, the United States Supreme Court became increasing interested in establishing rules for federal courts to evaluate states’ ballot access rules. On the one hand, the state has an interest in preventing an overcrowded ballot and ensuring that only serious candidates appear on it. On the other hand, the state’s rules may be unduly restrictive, which may reduce voters’ choices or entrench one or both major political parties in office. The Court has developed a balancing test to determine whether the rules are too onerous or whether the state has adequately justified its interest. These fact-intensive balancing tests have left federal courts with the task of figuring out these context-specific questions.