In litigation over the 2020 election, Texas and other Republican-led states showed exactly how that argument would work when they asked the Supreme Court to block the certification of Biden electors in four swing states. Texas argued that the election results in Pennsylvania, Georgia, Wisconsin, and Michigan were unconstitutional because “executive and judicial officials made significant changes to the legislatively defined election laws,” for example by changing deadlines for mail-in ballots because of the coronavirus pandemic. The Supreme Court made no ruling on the merits, declining to hear the case because Texas had no standing to sue.

But if the Supreme Court adopts the ISL doctrine in Moore, the argument that Texas made will become a model in 2024. The conditions that Texas cited in its argument are almost always present in contemporary elections. Legislatures pass laws on the conduct of the vote, but election administrators have to interpret those laws and set implementing rules such as precinct locations, polling times, and counting procedures. State courts sometimes mandate changes in the rules to comply with their state constitutions. It’s all but impossible to conduct an election without making rules or choices that the legislature did not specifically authorize.

The pernicious threat of ISL, wrote Richard L. Hasen, an election-law expert at UCLA, is that “a state legislature dominated by Republicans in a state won by Democrats could simply meet and declare that local administrators or courts have deviated from the legislature’s own rules, and therefore the legislature will take matters into its own hands and choose its own slate of electors.”