The religious, as opposed to ideological, composition of the U.S. Supreme Court has become less important to most people in recent decades. But it’s still being noticed that the proposed nomination of Elena Kagan to replace John Paul Stevens would create, for the first time, a Supreme Court with no professed Protestant Christians—instead, six Roman Catholics and three Jews.
When the burgeoning Catholic majority on the Court became an issue during the Sotomayor nomination debate, Andrew Gelman did a quick analysis here of the Court’s religious composition over the centuries, noting that Protestants were a long way from suffering any overall under-representation. It's a good time to look a little deeper at religious representation on the Court.
The Court has never been particularly representative of the public as a whole when it comes to religious diversity. The Catholic population of the US reached 12 million (or sixteen percent of the total population) by the beginning of the twentieth century, and has gradually increased ever since to well over seventy million (or one-fourth of the population). Yet today's six Catholics account for exactly half of the Catholic Supreme Justices ever appointed, out of 109 total (according to the most commonly cited source for this subject). That's compared to 35 Episcopalians, representing a denomination which has never numbered more than 3.4 million. Presbyterians (19 Justices) and Unitarians (10) are other grossly over-represented faith communities, while Baptists (3 Justices), Mormons (zero) and of course, the irreligious, are all under-represented.
It's interesting to compare the Supreme Court to the institution that reviews Court appointments, the U.S. Senate. In that body, Catholics (25) and Methodists (8) are almost perfectly represented as percentages of the population. As is the case historically with the Supreme Court, Presbyterians (14) and Episcopalians(7) are notably over-represented, but so too are Mormons (6), while Baptists (8) and the non-affiliated (none) are under-represented. There are also 13 Jews, with the most interesting historical factor being that none of them, for the first time since Jacob Javits was elected to the Senate in 1956, is a Republican.
If there is a lesson, it's that this is no longer a Protestant Nation, and that "fair" representation of religious communities in major national institutions takes some time. And since the unaffiliated are the least well-represented in public professions, it should be noted that they are undoubtedly well-represented in private practice. I'm reminded of the time when the wife of Sen. Bob Taft, then the leader of the conservative wing of the GOP, and the son of a Unitarian president and Chief Justice, was asked where her husband worshipped on Sunday mornings. "Burning Tree," she blurted out, referring to the congressional golf course. Such honesty is hard to imagine today.