Can a board add an executive session to an agenda after the meeting has started, even if the executive session wasn't included on the original meeting posting?

The short answer is yes. The chair must read out loud the statutory authority that allows the topic to be discussed in executive session, and the purpose for the session.

Oregon recognizes three "types" of meetings: Regular (those on the calendar adopted by the board at the July reorganization meeting), Special (all other meetings that come up throughout the year which require 24 hour notice) and Emergency (meetings which cannot wait for 24 hours to meet the posting requirements of a Special meeting).

Executive sessions are defined in ORS 192.610 (2) "Executive session" means any meeting or part of a meeting of a governing body which is closed to certain persons for deliberation on certain matters. Executive session can be held during a meeting (regular, special or emergency) when the agenda item topic qualifies for an exemption from the requirement that the public be able to observe the meeting. Sometimes all of the agenda items fall in this category, or there is only one agenda item at the entire meeting and it is an executive session item. Boards typically refer to these situations as an "Executive Session meeting" and the posting lists the statutory authority for the executive session and the purpose. The meeting must meet the requirements for posting as a Regular, Special or Emergency meeting.
Oregon's statute for posting meetings requires that you list the "principal subjects anticipated to be covered at the meeting but this requirement shall not limit the ability of a governing body to consider additional subjects" ORS 192.640 (1). Notice that it clearly states that the posting does not limit the topics discussed at the meeting. If something comes up during the meeting, you can add it to the agenda. This applies to both public session and executive session topics. You are simply adding an agenda item, just like any other. The chair must read out loud the statutory authority that allows the board to meet in executive session and state the purpose of the executive session agenda item.

The important point is that the "meeting" as a whole must have been posted. Once that notification of a public meeting hurdle has been met, you can add any last minute agenda items, public session or executive session, even though they were not on the originally posted agenda.

As is noted in the statute below if the executive session is the only agenda item, or all the agenda items are executive session items, you still must post the meeting. ORS 192.640(2) "If an executive session only will be held, the notice shall be given to the members of the governing body, to the general public and to news media which have requested notice, stating the specific provision of law authorizing the executive session." ORS 192.660(1) ORS 192.610 to 192.690 do not prevent the governing body of a public body from holding executive session during a regular, special or emergency meeting after the presiding officer has identified the authorization under ORS 192.610 to 192.690 for holding the executive session.
Remember when we talk about adding items to the agenda during the meeting we are talking about additions of items we didn’t know about or expect to discuss when the meeting was posted. It is always good practice to minimize last minute additions. You must post all of those items you expect to discuss at the meeting at the time of the posting, both regular public session agenda items, and executive session agenda items. If you start regularly talking about things that were not on the meeting posting the ‘court of public opinion’ will not like it, and it will lead to distrust in the process.
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