They were mostly or all Democrats?
I still blame “FJR” for the direction of the court during those years
John Paul Stevens, who wrote the majority opinion, had been appointed by President Ford. Anthony Kennedy had been appointed by Reagan. David Souter had been appointed by George H.W. Bush. Both Stephen Breyer and Ruth Bader Ginsburg had been Clinton appointees.
Thus, a 3-2 Republican-Democrat alignment among the Massachusetts majority. None of the five are on the Court today.
Chief Justice Roberts was appointed by George W. Bush. Clarence Thomas -- today, the most senior member on the Court in terms of years served -- was appointed by George H.W. Bush. Antonin Scalia (now deceased, of course) had been appointed by Ronald Reagan. Samuel Alito was appointed by George W. Bush.
Accordingly, at the time Massachusetts was decided (again, by a 5-4 vote), seven of the nine Justices had been appointed/nominated by Republican Presidents. Make of that what you will.