I did not have time when I was at the Library of Congress looking at Justice Stevens’ papers to give a close read to the file in Vieth v. Jubelirer, a 2004 partisan gerrymandering case. In that case, four Justices, led by Justice Scalia, took the view that such claims were not justiciable (that is, could not be heard) in federal courts. [This is the position that the Supreme Court eventually took in the 2019 Rucho case.] Four Justices, including Justice Souter, dissented. Justice Kennedy agreed with the Scalia group that the standards for policing partisan gerrymandering put forward by the dissenters did not work. But he disagreed with Scalia about non-justiciability, believing the issue should percolate longer. Scalia’s opinion was not for the Court, but a plurality opinion joined by 3 other justices.
In the file, I found that Scalia originally was writing a majority opinion for the Court, with Kennedy joining Scalia, Thomas, Rehnquist, and O’Connor. Between the 4th and 5th drafts, Kennedy advanced his lone view to keep the issue open but not embrace any standards. That 5th draft was still called a majority opinion, but Scalia began attacking Kennedy’s position in that draft.
Also, interestingly, Justice Souter began his dissent as an opinion concurring in the judgment, drawing a distinction between statewide claims and district by district claims.
I’m sure there’s a lot more to do with this file for someone who has time. You can find the selected documents I copied at this link.