The U.S. Supreme Court’s April hearing and June ruling on same-sex marriage will be historic for the nation’s religions as well as for partisan politics, law, and society. There’s sharp division in this case among faith groups, and sometimes within them, so reporters will want to carefully monitor the inflow of religious and moral arguments as “friend of the court” briefs are filed in coming weeks.

The court defines two issues: Does the Constitution’s “equal protection” clause require that all states issue same-sex marriage licenses? Does the same clause require that a state recognize all marriages lawfully licensed by other states?

An implicit issue: whether judges or state legislatures and voters have power over contested social policies.

Religious proponents of marriage change are confident of Supreme Court victory and likely to file briefs. They include liberal Jews, Unitarian Universalists, and the Metropolitan Community Churches (whose primary ministry is with gays, lesbians, bisexuals and the transgendered), along with organizations of atheists and humanists.  Defending traditional marriage  are the the leaders of the Roman Catholic Church, Eastern Orthodoxy, evangelical and conservative Protestants, some African-American Protestants, the Church of Jesus Christ of Latter-day Saints (“Mormon”), Orthodox Judaism and Islam.

But what about the so-called “Mainline” Protestants who’ve lately been shifting -- especially at the level of pulpits and church boards -- in favor of gay couples?

Want to find a source for some crucial facts that can be attributed to a good source?

Years ago, this family of long-established, predominantly white and relatively affluent denominations  strongly influenced American culture on pressing issues of the day. In recent times Mainliners have continued to speak out, but with diminished impact (though some disagree with that). But they’ve been remarkably absent on important legal disputes.

Consider the Supreme Court’s 2013 “Windsor” and “Hollingsworth” gay-marriage cases. Thanks to the invaluable www.scotusblog.com we can quickly see that not a single Mainline denomination filed a friend-of-the-court brief in its own name.

California’s Episcopal bishops and a United Church of Christ unit via the California Council of Churches filed briefs, but neither of the national denominations. The National Council of Churches avoided the case, while the National Association of Evangelicals filed as part of an unusual alliance including the Mormon church and Union of Orthodox Jewish Congregations. The conservative Lutheran Church-Missouri Synod filed while the Evangelical Lutheran Church in America did not. The Presbyterian Church (USA) was also among the missing.

There was some Mainline involvement in a second-hand way. The Anti-Defamation League filed a pro-change brief joined by the Religious Coalition for Reproductive Choice (originally formed to promote abortion liberalization). The Coalition, in turn, represents the Episcopal Church, United Church of Christ, and United Methodist Church Board of Church and Society (though the Methodist church itself teaches against gay relationships.)

By sidestepping the 2013 case the Mainliners avoided related religious-liberty issues that were raised instead by the American Jewish Committee (AJC). Its brief urged legalized gay marriage but also warned the justices that courts’ wordings will affect such practicalities as religious adoption agencies, employment and spousal benefit policies, housing at religious colleges, and so forth:  “Religious organizations will face lawsuits, civil penalties, and loss of government benefits.”

So here is the main tip from that. That brief’s authors, Marc Stern of the AJC and University of Virginia law Professor Douglas Laycock, should be on every journalist’s prime source list as those issues grind away over the next decade or two.

The Religion Guy provided further background in articles that analyzed U.S. religious groups’ viewpoints and the relevant Bible passages.