Arizona law prohibits any voter from "knowingly vot[ing] more than once at any election." Ariz. Rev. Stat. § 16-1016(2). Carol Hannah sent a mail-in ballot in Colorado for the Colorado elections, and she subsequently voted in person in the Arizona general election held November 2, 2010. She was found guilty at a jury trial.

On appeal, in State v. Hannah, 2015 WL 4538536 (Ariz. Ct. Ap. July 28, 2015), the court noted that this was not prohibited by the statute, even though the elections were held on a single day pursuant to federal law:

The State argues the Arizona and Colorado elections held on November 2, 2010 were part of one election, relying on congressional regulations that designate a specific day to select candidates for Congress and the President in a singular, regular election. See 2 U.S.C. § 1 (setting the day for “the regular election held in any State” to choose Senators); 2 U.S.C. § 7 (establishing “the day for the election” of Representatives and Delegates to Congress); 3 U.S.C. § 1 (setting date for “every election” of President and Vice President).

We recognize the elections held on the first Tuesday following the first Monday of November in every even-numbered year are sometimes referred to as “national elections” because they, collectively, include the selection of all the members of the House of Representatives and one-third of the members of the Senate. However, these state elections are held on the same day as a matter of administrative and practical convenience in an attempt "'to remedy more than one evil arising from the election of members of Congress occurring at different times in the different States.'" Foster v. Love, 522 U.S. 67, 73 (1997) (quoting Ex parte Yarbrough, 110 U.S. 651, 661 (1884)). But, within that singular time constraint, each state conducts a separate election for the selection of its Senators and Representatives as constitutionally provided. See U.S. Const. art. I, § 4, cl. 1 (reserving to the states the authority to prescribe the time, place, and manner of holding elections for its Senators and Representatives); United States v. Classic, 313 U.S. 299, 311 (1941) (stating that under the Elections Clause, “the states are given, and in fact exercise wide discretion in the formulation of a system for the choice by the people of representatives in Congress”).

Thus, the elections held in Arizona and Colorado on November 2, 2010, although occurring on the same day, were separate and discrete elections, held in two different states. While the evidence is sufficient to permit a finding that Hannah cast a ballot in both Arizona and Colorado on November 2, 2010, the evidence is insufficient to show Hannah voted “more than once in any election,” such that her vote received more weight than that of any other citizen, where there is no evidence that any candidate appeared on both ballots and 2010 was not a presidential election year. The evidence is therefore insufficient to support a conviction for illegal voting in violation of A.R.S. § 16–1016(2), and we reverse the conviction.

Of note, however, is that other problems may exist with Hannah's decision to vote in two states:

Although we reverse Hannah's conviction, we do not mean to imply that voting in elections held in two separate states on the same date is otherwise proper or lawful. Such conduct raises serious questions regarding whether Hannah was a qualified voter in both Arizona and Colorado in November 2010. However, the State does not dispute Hannah was qualified to vote in the Arizona election, and Hannah was not charged with casting a vote while not qualified to do so. See A.R.S. § 16–1016(1) (“A person is guilty of a class 5 felony who ... [n]ot being entitled to vote, knowingly votes.”). Whether Hannah was qualified to cast a ballot in the Colorado election is a matter for Colorado to address in the interpretation and application of its own law. We likewise express no opinion as to whether Hannah's conduct constitutes a violation of federal law. See, e.g., 52 U.S.C. § 10307(e) (prohibiting voting more than once in a federal election).

It's an interesting little statutory interpretation question with a constitutional dimension, and it invites scrutiny and more careful drafting of other kinds of double-voting laws in an age where early voting is increasingly widespread.