Not sure if the majority of justices at the time were appointed by Democrats or not. But there were some great decisions made by a few GOP appointed justices in the past. But that was a long time ago. The justices who stood for civil rights have passed on.

http://en.wikipedia.org/wiki/List_of_Justices_of_the_Supreme_Court_of_the_United_States

the chart isn't laid out in a way that's easy to answer your question, but it looks like we had a majority in 1969 (based solely on the president's party affiliation), and lost it with fortas's resignation and replacement with nixon's appointment of blackmun.

for 1969 it was:

black (fdr)
douglas (fdr)
white (jfk)
fortas (lbj)
marshall (lbj)
----
harlan (dde)
brennan (dde)
stewart (dde)
burger (rmn)


that said, party affiliation of the president doesn't always indicate the leaning of the justice, or at least it didn't. around that time. nixon's appointments in particular covered a wide range of the political spectrum.

Eisenhower had four appointments. (Earl Warren, who Nixon got to replace with Burger in 1969, was also an Eisenhower appointee.) Truman also had four appointments but they were all long gone before 1969. In fact three were gone during Eisenhower's terms.

You can never predict how much or little influence a President is going to have on the Court. Ford thought he was moving the Court to the right by replacing Douglas, but put one of the more reliable liberal votes on the Court. Same thing with Bush the First and Souter.

It's amazing that there has been a Republican appointed majority for 40 plus years.

It would be a dream come true for Obama to get re-elected and flip a conservative seat or two.