The Supreme Court is sowing confusion over how it will handle election disputes this fall

(CNN) – The recent U.S. Supreme Court decision changing voter registration rules in Arizona has voting rights advocates anxious about how the justices will approach emergency election appeals in the runup to the November election.Not only was the Arizona ruling a missed opportunity for the justices to explain when they will engage in election and voting cases, experts say it has also heightened concern that the court is unevenly applying a murky legal principle intended to reduce chaos rather than add to it.The “Purcell principle,” rooted in a 2006 Supreme Court decision, warns federal courts to avoid making last minute changes to the status quo of voting rules before an election.But 18 years later, what counts as “status quo” and “last-minute” still remains up for debate. That lack of clarity – and what critics see as an inconsistent application of the doctrine – could be a critical factor in this year’s election.The Arizona ruling “is creating additional uncertainty around a principle that already had very few concrete parameters,” said Sophia Lin Lakin, director of the ACLU’s Voting Rights Project. “It’s hard to understand exactly what the court is doing when it comes to Purcell and that creates a lot of...