23. IRV faces no obstacle from federal laws or the federal constitution
For state elections, there is certainly no federal restriction. Many states and municipalities have used a variety of preference voting systems. But what about Vermonts federal elections, President/Vice president electors, U.S. Senators, and U.S. Representative? Is there a federal restriction on voting systems? There are some regulations, but none that would preclude IRV.
The constitutional requirements are few. They include: The requirement that Congress be chosen by the citizenry (Article I sec. 2: states "The House of Representatives shall be composed of Members chosen every second Year by the People of the several States..."); that the state legislatures shall decide the voting system subject to override by Congress (Article I sec. 4: states "The Times, Places and Manner of holding Elections for Senators and Representatives shall be prescribed in each State by the Legislature thereof; but the Congress may at any time by Law make or alter such Regulations, except as to the Place of chusing [sic] Senators."); that Congress shall rule on disputes over an election of a member (Article I sec. 5: "Each House shall be the Judge of the Elections, Returns and Qualifications of its own Members..."); the voting system for selecting members of the electoral college is solely the responsibility of the state legislature except as to the timing, (Article II sec. 1: The President and Vice-President shall "be elected as follows Each State shall appoint, in such manner as the Legislature thereof may direct, a Number of Electors, equal to [the number of Representatives and Senators combined]...The Congress may determine the Time of chusing [sic] the Electors, and the Day on which they shall give their Votes; which Day shall be the same throughout the United States.").
There are only two restrictions Congress has applied to how states conduct federal elections. The first restriction is a prohibition against electing U.S. Representatives from at-large districts of more than one seat. This is irrelevant for Vermont, as we currently have only one Representative, although that number is not set in the Constitution and could be raised by a change in the law that put a cap on the size of the House. The second restriction is an 1872 law that prohibits any state from holding a decisive election for a federal office on any date prior to the national date. This law was cited when the Supreme Court threw out a Louisiana voting system used from 1975 till this year, wherein an open, unitary primary, allowed a winner with more than 50% of the total vote to be declared elected in October without any November election. Neither of these restrictions would have any impact on Vermonts adopting IRV.