8-9. Elders being of one class of office, ruling elders possess the same authority and eligibility to office in the courts of the Church as teaching elders. They should, moreover, cultivate zealously their own aptness to teach the Bible and should improve every opportunity of doing so.

[Historical Summary : The current text dates to a chapter-wide revision enacted in 1980 (M8GA, 8-88, p. 112). By deleting the final portion of the second sentence found in prior PCA texts and PCUS editions back to 1888, the question occurs whether the 1980 revision was designed to be more open-ended by being less specific, or whether the revision was intended to curtail Ruling Elders from acting as lay pastors? For further background on the older editions, see under the Commentary section below an excerpt from E.C. Scott's Assembly's Digest.]

BACKGROUND & COMPARISON:
1. PCA 1973, 9-2, Adopted text, M1GA, Appendix, p. 131
2. Continuing Presbyterian Church 1973, 9-2, Proposed text, p. 9
3. PCUS 1933, X-§41
4. PCUS 1925, X-§41
and
5. PCUS 1888 (cf. PCUS Minutes, p. 424)
These Ruling Elders possess the same authority and eligibility to office in the courts of the Church as the Ministers of the Word. They should, moreover, cultivate zealously their aptness to teach the Bible and should improve every opportunity of doing so, to the end that destitute places, mission points, and churches without Pastors may be supplied with religious services.

PCUS 1879, IV-3-2
These Ruling Elders do not labour in the Word and doctrine, but possess the same authority in the courts of the Church as the Ministers of the Word.

PCUS 1869 draft, IV-3-2
These Presbyters, as ecclesiastical rulers, possess the same authority with the Teaching Elder.

PCUS 1867 draft, IV-3-2
These presbyters, as ecclesiastical rulers, are of the same rank, and possess the same authority with the teaching elder. And while the titles of bishop, pastor, and minister, belong to the teaching elder by way of eminency, because he excels by reason of his entire consecration to the work, as well as by the superiority of his functions, they also belong to the office of the ruling elder, seeing that, in order to rule with diligence, he must take the oversight of the flock; in order to its protection he must guard and guide it; and in order to discharge the chief duty of his office, he must serve Christ diligently in the exercise of government.

COMMENTARY :
F.P. Ramsay, Exposition of the Book of Church Order (1898, p. 55-56), on IV-3-2 :
43.--II. These Ruling Elders do not labour in the Word and doctrine, but possess the same authority in the courts of the Church as the Ministers of the Word.
officially (for nothing is here decided as to what others than Ministers of the Word may do unofficially in the Word and doctrine),
but possess he same authority in the courts of the Church as the Ministers of the Word.
May he then be Moderator of a court, and of the higher courts as well as of a Session, seeing that to Moderators are assigned certain duties that only Ministers can perform? Yes.
When, however, a Ruling Elder is Moderator of a Presbytery, Synod, or General Assembly, any official duty devolving on him, the performance of which requires the exercise of functions pertaining only to the teaching Elder, shall be remitted by him for execution to such Minister of the Word, being a member of the court, as he may select.
The Minister must be a member of the same court, so that he may be under the control of the court. It is to be observed that by a court consisting of the Word, men may be appointed to ministerial functions, and are subject to the control of the court, the power of government extending over the Church and its officers in all their functions. It is also to be observed that the Moderator is appointed to a special work by a court, and is answerable to the court appointing him. It is further to be observed that there is no fundamental principle requiring that the Moderator shall be of this or that class of Elders; but, since, as a matter of conveniency and prudence, certain ministerial functions are, in the detailed regulations of the Form of Government, assigned to the Moderator, the principles of the system do require either that these regulations should be abolished, or that Ruling Elders be kept out of the position of Moderator, or that a special provision, such as this, determine the assignment of ministerial functions. Provision is made elsewhere as to the Moderator of the Session.

Scott, E.C., A Digest of the Acts and Proceedings of the General Assembly of the Presbyterian Church in the United States, 1861-1944 (Richmond, VA : Presbyterian Committee of Publication, 1945), p. 64 :
Elders may be appointed by the Presbyteries to conduct services in neighboring congregations.
1866, p. 37. Resolved that every presbytery be enjoined to require the sessions of the vacant congregations to come up to the discharge of the duties devolved upon them in the twenty-first chapter of the Form of Government, in assembling of their respective congregations for the worship of God, to which it may be proper to add exhortation. And in order that this duty may be performed to the greater acceptance of the worshippers, it is further required that the presbyteries do seek out those elders who have the best gifts, and do especially appoint them to the performance of these duties.
1867, p. 148. [In answer to an Overture from the Presbytery of East Alabama:] Resolved, that the action of the last Assembly, on pp. 36 and 37 of the Minutes, is hereby reaffirmed, and the parts relating to the services of elders explained to mean, substantially, that, in accordance with our Constitution, when a vacant congregation does not enjoy the services of any elder, who, for any proper reason, is competent to perform the duties contemplated, it shall be the duty of the presbytery to appoint an elder or elders from some neighboring congregation ; provided nothing herein contained shall be regarded as justifying a presbytery in extending its jurisdiction within the bounds of another.
1919, p. 51. From the Presbytery of Central Texas, asking that active steps be taken to use more fully capable ruling elders in conducting services in our vacant churches, in view of the absence of so many ministers engaged in war work.
Answer : The law of the Church already gives to churches and elders full opportunity in this matter. In view of the present need, the Assembly urges a fuller use of this opportunity.
1943, p. 76. That our ruling elders be called on to help look after pastorless churches in the absence of so many pastors now serving as chaplains in our Army and Navy, remembering their ordination vow, "to take oversight of the spiritual interests of the particular church committed to their charge".
[See also this Digest, Form of Govt., Par. 25.]