U.S. Senator John McCain died on August 25, 2018. On November 28, some Arizona voters filed a federal lawsuit, arguing that Arizona must hold a special election to fill the remainder of his seat before November 2020. The McCain seat would normally have been up for an election in 2022. The Arizona government believes it is constitutional to hold the first special election for the McCain seat in November 2020.
The case is Tedards v Ducey, 2:18cv-4241. Here is the Complaint. The lawsuit’s in-state attorney is Michael Kielsky, former chair of the Arizona Libertarian Party. The case will not be easy to win, because the federal courts in New York ruled in the past that it does not violate the Constitution for New York to have waited to fill U.S. Senator Robert Kennedy’s seat until November 1970. Kennedy died in June 1968.