The Seventeenth Amendment, ratified in 1913, provided for the direct election of United States senators, replacing the original method that had left the choice to state legislatures. Previously, state legislatures could choose senators and fill vacancies at any time during a regular or special legislative session. After the ratification of the Seventeenth Amendment, it was recognized that the expense and inconvenience of election by popular vote made it necessary to schedule elections for senators at regular intervals. To avoid the hardship to a state’s suffering a lack of representation pending a regular election, the Seventeenth Amendment also provided for methods of election or appointment to fill any unexpired term.

The language and history of the clause indicate that the states have the power to balance conflicting goals of a speedy popular election against the states’ interests in conducting elections on a regularized basis so as to maximize voter participation and minimize administrative expense. Thus, when the death of Robert F. Kennedy created a vacancy in New York’s Senate delegation in June 1968, New York was permitted to postpone the election of his replacement until 1970, rather than being required to hold both a primary and general election by the fall of 1968. Valenti v. Rockefeller (1969). Following the death of Senator John Heinz in 1991, Pennsylvania was permitted to fill the vacancy by a special election, with the candidates to be chosen by party conventions of the state’s two major parties. The Court held that the Seventeenth Amendment did not mandate that party nominees be chosen by popular vote, so long as the actual election was  by popular vote. Trinsey v. Pennsylvania (1991). In 2008, Roland Burris was appointed by the governor of Illinois, Rod Blagojevich, to fill President-elect Barack Obama’s Senate seat. (Blagojevich was later impeached and imprisoned for bribery and corruption charges related to his activities in connection with filling the vacancy.) Echoing Valenti, the Court found no violation of the Seventeenth Amendment when a special election was not called before a regularly scheduled general election, but it found that a writ of election must be issued. Judge v. Quinn (2010). See also S. J. Res. 7, 111th Cong., “A Joint Resolution Proposing an Amendment to the Constitution of the United States Relative to the Election of Senators” (2009) and H.R. 899, the Ethical and Legal Elections for Congressional Transitions Act (2009).

The clause does not define when a vacancy exists. During the 2000 election, the people of Missouri knowingly voted for the deceased Mel Carnahan. The governor declared this election to have created a vacancy, which he filled by appointing Carnahan’s widow, Jean Carnahan, and he then issued a writ of election for 2002. It remains an open question, however, whether the voters can create a Senate “vacancy” by knowingly voting for an ineligible candidate and allowing the governor to fill the position with an individual of his choice, as opposed to simply declaring the votes to be improper or “spoiled” ballots.

Renewed interest in the Senate vacancy clause has arisen because of the controversy surrounding the appointment of Roland Burris and the Massachusetts legislature’s political machinations to assure a Democratic appointee after the death of longtime Senator Edward Kennedy. Bills were considered that would have seated only senators who were elected by the people. One commentator has argued that the original understanding of the Seventeenth Amendment would not have led to the result in Quinn that required a writ of election to be issued when it was inconsistent with procedures set up by a state legislature. Others have debated whether Congress has the authority to require states to establish uniform procedures to fill vacancies or whether a constitutional amendment is necessary.