A NYT Sidebar column by Adam Liptak, "‘Politicians in Robes’? Not Exactly, but . . ." examines the question of the extent to which a judges' partisan origins affect their judgments, and uses the 6th circuit's recent MIchigan affirmative action decision as the linchpin of the piece. The piece is, at least, a useful compilation of research on the obvious, which is that partisan labels misrepresent the function of a judge but that knowing which party nominated a judge can be a good predictor of the judges' votes on certain issues. The piece also references this interesting note from SCOTUSblog's Lyle Denniston, reporting on the Michigan decision:
Readers will find, in some news accounts about this decision, references to the political party affiliation of the presidents who named the judges to the bench, referring to them as Republican or Democratic appointees. The author of this blog [SCOTUSBLog] will provide that information only when it is clearly demonstrated that the political source of a judge’s selection had a direct bearing upon how that judge voted — admittedly, a very difficult thing to prove. Otherwise, the use of such references invites the reader to draw such a conclusion about partisan influence, without proof.
This blog is also so inclined, for reasons stated here.