The Upshot has compiled data on which justices agree with each other most often. Their findings might surprise readers who are not obsessive court watchers.
So the two justices who vote together the most often is Justices Scalia and Thomas, right? Nope. They’re not even in the top three pairs.
Looking at the past four terms (including the current term) the two justices who agree most often are Justices Kagan and Sotomayor (94%). The next most common pairing is the Chief Justice and Justice Alito (93%), followed by Justices Kagan and Ginsburg (92%).
Over the time period at issue, Justices Scalia and Thomas agreed 90% of the time, as did Justices Alito and Thomas and Justices Sotomayor and Ginsburg.
Justice Kennedy, who is so often the swing vote on the current Court, agreed with the Chief Justice more often (88%) than he did with any other justice.
Note with a few more almost-certainly divided opinions yet to be issue this term, it’s possible some of the numbers above could change.