Sixteen Protestant denominations and regional districts have joined a friend-of-the-court brief supporting the Episcopal Diocese of Virginia in contesting a Reconstruction-era state law that governs church splits.

The post-Civil War splintering of Methodist and Presbyterian churches in 1867 prompted the Virginia law, which allows congregations to keep their property when seceding from a church or "religious society" that's dividing.

This spring, however, the United Methodist Church and the Presbyterian Church (USA), two of the largest U.S. mainline Protestant denominations, say the law is unconstitutional.

On Friday, a judge in Fairfax County, Va., ruled that the UMC, the African Methodist Episcopal Church, the African Methodist Episcopal Zion Church and the Worldwide Church of God may participate in oral arguments May 28 to assess the law's constitutionality.

The amicus curiae brief is a sign of how closely Protestants are following the multimillion-dollar battle between the Episcopal Church and 11 conservative congregations that left to join a branch of the Anglical Church of Nigeria.