I think that Paul makes it clear that the elders of the church must be able to define, declare, and defend the truths of God’s Word (e.g. Acts 20:28-32; Titus 1:9).
What also appears evident in the New Testament is that it is not just the elders who are to declare and defend the truths of God’s Word (e.g. Romans 15:14; 1 Thessalonians 5:12-15). I note with interest that in Acts 20:28ff. Paul warns that some of those who depart from the truth may be from among their own number (verse 30). Thus, later on – in 1 Timothy chapter 1 – it is Timothy whom Paul sends to correct false teaching at Ephesus (1 Timothy 1:3-4). In chapter 5 Paul gives instructions for removing an elder. In Ephesians 4:1-16 we see the building up of the body (so as to be able to recognize and stand against false teaching) as a corporate matter, and not just an “elder” function. So, too, in 1 Corinthians chapter 14 (which I perceive to be Paul’s description of the meeting and ministry of the church body when gathered). Correction is certainly implied, but is more interactive in nature, and elders are not specifically mentioned (1 Corinthians 14:26-33).
Second, there are other ways to protect the church’s ability to hold fast to sound doctrine. For example, you can have a doctrinal statement as a part of your constitution. The only caveat here is that one would hope that our understanding of Scripture might grow, and it is not always easy to change the constitution. In our church where I serve we have dealt with doctrinal error by teaching a text (or in one case the Book of Galatians) which clearly instructs in sound doctrine and exposes error.
Third, I believe that there is a difference between defining and defending sound doctrine and being the sole interpreter of Scripture. Indeed, in 1 John 2:26-27 John seems to warn Christians in general against signing over their responsibility to personally wrestle with God’s Word and to come to their own conclusions, with the help of the Holy Spirit. Gifted teachers and elders who are “apt to teach” can certainly aid us in learning how to interpret Scripture, but they are not to do all our thinking for us! A church that is characterized by many who know the Scriptures is one that will stand in times of persecution (when their leaders may be jailed or put to death or become sick).
Fourth, when it comes to church discipline in regard to doctrinal error, there may very well be concerns about possible litigation. Some churches may seek to protect themselves by inserting statements into the church constitution which designate the elders as having exclusive authority to interpret Scripture. While there is little doubt that the church in America is going to face greater opposition (and even persecution) in the future, we must assess the wisdom and biblical basis for seeking to protect ourselves. A friend, fellow-elder, and highly respected lawyer used to remind us (elders), “We haven’t been sued yet. . .” His point was that if we are faithful to God’s Word we can expect opposition, and this will likely include lawsuits. I know of one or more faithful, well-known churches that have dealt with more than one lawsuit. It is part of doing God’s business. I think one of the reasons why churches today do not practice church discipline is their fear of such a lawsuit. We need to be “wise as serpents and harmless as doves” in a world that is hostile to our Lord, His Word, and His church, but we cannot be so obsessed with self-protection that we shy away from following the Scriptures. Thus, I would caution against any recommendation that over-reacts by designating the elders as the sole authoritative interpreters of Scripture – that would that would go beyond Scripture.