The moderator of the first General Assembly of the Presbyterian Church in America was a ruling elder–the Hon. W. Jack Williamson. Since that time, the PCA has established a tradition of alternating between ruling elders and teaching elders in its nomination and election of moderators for the General Assembly. But this practice remains unusual among Presbyterian denominations. Even within our own ecclesiastical heritage, it wasn’t always so, as Rev. R.C. Reed explains in this review of the PCUS General Assembly of 1914 :

“The Assembly elected a ruling elder to preside over its sessions. The law which makes the ruling elder eligible to the moderatorship of all our church courts is but a corollary of a fundamental principle of Presbyterianism–the parity in authority of all Presbyters. Our church did right to put this corollary into the form of law, and it ought not to suffer the law to lapse into a condition of innocuous desuetude. We cannot be accused of working it overtime. The law was enacted in 1886. It was seven years after that date before it received its first practical recognition in the election of Hon. J.W. Lapsley. Only four ruling elders have presided over our Assemblies in the twenty-eight years since the way was open for them to be honored with this responsibility. Always there is good material among the ministerial members to fill the office, as there was in the last Assembly, and there is never any reluctance on their part to serve, but they, as well as others, allow the propriety of occasionally electing a ruling elder in order to do justice to the principle of parity.”

[excerpted from “The General Assembly of 1914” by R.C. Reed, in Union Seminary Review 26.1 (October 1914): 4.]