Martha McSally participates in a mock swearing-in during the opening day of the 116th Congress on January 3, 2019.Aaron Bernstein / Reuters

On election day 2018, the voters of Arizona went to the polls to replace their retiring Republican senator, Jeff Flake. The election was so close that it took six days to reach a final result. But in the end, the Democrat Kyrsten Sinema defeated the Republican Martha McSally by 56,000 votes out of 2.8 million cast.

On January 3, 2019, Sinema was sworn in as a member of the Senate. Standing next to her, and taking the same oath, was McSally—appointed by the state’s Republican governor to take over the remainder of the late Senator John McCain’s term. The two will serve side by side until January 2021.

This anomalous result stems from an ambiguity in the Seventeenth Amendment that politicians have exploited for partisan advantage since the amendment was adopted in 1913. A new lawsuit, aimed at McSally’s appointment, seeks to resolve it. At stake in Tedards et al. v. Ducey et al. is nothing less than the principle that the Senate belongs to the people.

The Seventeenth Amendment specifies that U.S. senators are to be “elected by the people” instead of by state legislatures, as originally provided by the 1787 Constitution. Ratification came after more than two decades of sustained, organized mobilization by ordinary Americans outraged by the corruption of state legislators who sold Senate seats to the highest bidders. The hitch? Section 2 of the Seventeenth Amendment permits appointment by governors in the event of a vacancy: “The executive authority of each state shall issue writs of election to fill such vacancies: provided that the legislature of any state may empower the executive thereof to make temporary appointments until the people fill the vacancies by election as the legislature may direct.”

The vacancy language is left over from the old legislative-appointment system, under which governors could appoint temporary senators “until the next Meeting of the Legislature.” Those “temporary appointments” were limited in time—they could not last beyond the next legislative session, which was already set by state law. But the drafters of the Seventeenth Amendment, for whatever reason, specified “temporary appointments until the people fill the vacancies by election as the legislature may direct.”

See the difference? The special Senate election has no firm deadline, and the language could even be read to allow a “temporary appointment” to substitute completely for a special election.

The amendment’s language does not require appointments; it permits them if a state legislature chooses. At present, five states require immediate special elections, nine allow a genuinely temporary appointment followed by prompt special elections, and 36 allow the appointed senator to serve until the next general election—or even for the remainder of the departing senator’s term. Six of the appointment states, including Arizona, require the appointee to belong to the same political party as the departing senator.

Ambiguities aside, long-term appointment seems contrary to both the language and the spirit of the amendment; so does the same-party requirement. Legislatures should facilitate, not impede, popular elections—and they certainly shouldn’t be deciding which party gets the seat over a long period.

Some politicians see things otherwise. Control of a Senate seat is, to quote former Illinois Governor Rod Blagojevich, “a fucking valuable thing.” Blagojevich shared these musings on a federal wiretap in late 2008, when he had the chance to fill the seat vacated by President-elect Barack Obama. Although there’s no evidence that Blagojevich was able to cash in on the appointment, the crassness with which he tried to do so was one of the reasons he was impeached by the legislature and then sent to a federal prison.

Before then, Blagojevich had appointed Roland Burris to the seat; under Illinois law as it stood, Burris was to serve until 2011—the entire remainder of Obama’s term. But two Illinois voters sued over the appointment. Their claim was that the amendment requires “temporary appointments” and a special election. A statute that gave the entire remaining term to an appointee violated that provision because it was not “temporary,” and no special election would be held.

Their legal team was headed by Tom Geoghegan, a college classmate of mine who has devoted his career to fighting for labor unions and progressive causes. Geoghegan gave me the chance to run down some historical details on the passage of the amendment and subsequent cases brought under it. Eventually, the U.S. Court of Appeals for the Seventh Circuit agreed with our theory. It ordered Illinois to hold a special election.

This was an almost completely symbolic victory—by the time the court case ended, the regular 2010 Senate election was only weeks away. Nonetheless, the state complied by holding two elections on November 2, 2010. One was for the full six-year term beginning in January 2011; the other was for the month remaining in Burris’s term. The Republican nominee Mark Kirk won both; he took office within days—which gave him a seniority bump over that cycle’s 16 other Senate newcomers.

Symbolic or not, Judge v. Quinn recognizes the important truth about the Seventeenth Amendment: Election by the people is the norm. “Temporary appointment” is there to facilitate self-government, not as a gift to the Blagojeviches of the world.

Geoghegan and his associates are now challenging the McSally appointment, with Judge v. Quinn on their side.

What happened in Arizona doesn’t involve financial corruption, just old-style party power-seeking. When McCain died in August of last year, Republican Governor Doug Ducey originally appointed former Senator Jon Kyl to replace him. At that time, Sinema and McSally were fighting for the other open seat. Once Sinema won that seat, Kyl resigned—and Ducey named McSally to the office that the state’s voters had just chosen to deny her. Democrats won the 2018 election in Arizona and across the nation, but the statute made McCain’s seat the exclusive property of the defeated party.

Geoghegan’s Arizona lawsuit, Tedards et al. v. Ducey et al., pits five voters (two Democrats, one Republican, one independent, and one libertarian) against Ducey in his capacity as governor. The voters argue that the 27-month delay in holding an election is “just too long” and, beyond that, violates the requirement of a special “writ of election.” Second, they say, the Seventeenth Amendment allows legislatures to “empower” governors to make appointments, but Arizona’s law “requires” an appointment, and further, limits the potential appointee by political party—neither of which, they say, the amendment allows. Third, they allege, the partisan-affiliation requirement is an attempt to add a new qualification to those spelled out in the Constitution’s article 1 (senators must be 30 years old, have been citizens for at least nine years, and be “inhabitants” of the state), which the Supreme Court has held that state legislatures cannot do.

Ducey’s lawyers argue that the 27-month delay is reasonable, that the appointment and party-requirement statute “favors no political party,” and that asking the voters to participate in a special election will upset them: “Special elections are inconvenient and confusing for voters, who must make time to participate in additional rounds of primary and general voting and deal with yet another highly politicized election year immediately after the conclusion of a contentious election cycle.”

What the federal court will make of this challenge is hard to predict. The amendment’s wording, as I’ve noted, is ambiguous. And a judge might wonder whether “just too long” is a manageable standard for deciding when special elections must be held.

The Supreme Court has been largely silent on this issue. The one exception, of sorts, was Valenti v. Rockefeller. In that case, New York voters demanded a special election to fill the seat left vacant by the 1968 assassination of Senator Robert Kennedy. They wanted an election in five months; the lower courts rejected that claim. The Supreme Court agreed in an opinion reading, in full, “The motion to affirm is granted and the judgment is affirmed.” Scholars have argued over the meaning of that opinion ever since.

The historical record on the amendment’s appointment provision isn’t much help, either. “What is perhaps most remarkable about deliberations over the Seventeenth Amendment in both chambers is how little was said of the vacancies clause,” Thomas Neale, a Congressional Research Service specialist, wrote in a CRS report last year. Neale quotes Senator Joseph Bristow, the amendment’s chief sponsor, who said that the language

is practically the same provision which now exists in the case of such a vacancy. The governor of the State may appoint a Senator until the legislature elects. My amendment provides that the legislature may empower the governor of the State to appoint a Senator to fill a vacancy until the election occurs, and he is directed by this amendment to “issue writs of election to fill such vacancies.”

As we have seen above, Bristow was wrong about how the language would be read. The point of the amendment was to remove corrupt legislators from Senate elections; the wording has allowed them to slither back in.

One Senate vote can be a consequential thing. The Republican plan to repeal the Affordable Care Act, for example, failed in 2017 by one vote—John McCain’s. Now the very seat that McCain vacated has been handed unilaterally to a lawmaker who owes the seat not to the voters who rejected her but to a Republican governor and his party.

If another crucial measure hangs by one vote in the next two years, voters can fairly wonder whom McSally will consult before casting hers.

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