A recent case out of South Carolina is drawing attention to the potential impact of open primaries on election results. South Carolina law does not require voters to formally register with a particular political party in order to cast a vote in a primary. A system in which voters can select the primary they wish to vote in regardless of party affiliation is called an open primary system. Open primary systems sometimes draw criticism because they can allow voters to engage in so-called crossover voting. Crossover voting occurs when members of one political party deliberately vote for a candidate they perceive to be weaker in an opposing party’s primary in order to give their candidate an advantage. It is important to note that voters in an open primary system do have to select only one primary in which to vote, so crossover voting naturally removes a voter’s opportunity to cast a ballot for the actual candidate of her choice in her own party’s primary. Exit polls provide evidence that voters have crossed party lines during primaries in South Carolina. For example, despite South Carolina’s traditionally conservative electorate, nearly 30% of the voters in the Republican presidential primary in 2012 were either Democrats or Independents. Further, nearly a quarter of the independents chose Ron Paul as their candidate of choice, rather than the eventual winner in the primary, Newt Gingrich.
The open primary scheme came under fire in a 2010 lawsuit initiated by the Republican Party of Greenville County, South Carolina, along with the state Republican Party. The GOP sued the Chairman of the South Carolina State Election Commission, alleging that the open primary system infringed on the Party’s right to freedom of association. In a surprising twist, the South Carolina Republican Party withdrew from the suit in June, leaving the Greenville County Republican Party as the sole plaintiff. On August 21, Judge Mary Lewis held that the Greenville County Republican Party lacked standing to sue and dismissed the case. Judge Lewis based her holding on two main factors. First, South Carolina law provides state, local, and municipal parties with alternatives to nominating candidates through primaries, including nomination through convention or write-on during the general election. The presence of these options caused the Greenville GOP to fail on the causation and redressibility prongs of their claim since the Party could simply elect to nominate the candidate of their choice by convention, completely excluding any non-republican voters. The rub of the South Carolina nomination by convention law lies in the fact that three-fourths of the party must vote in favor of that option. Second, Judge Lewis believed that the Greenville branch of the Republican Party was attempting to recover based on associational injuries that could only be asserted by the statewide party.
Independents count the court case as a major victory. One group that filed an amicus brief in the case notes that closed primary systems can preventindependents from voting in the first round of elections, and closed primaries have proved problematic for minority voters in the past.