ABA Formal Opinion 518 Sparks Debate Over Mediator Ethics and Settlement Proposals

ABA Formal Opinion 518 has sparked continuing debate within the alternative dispute resolution community over the ethical responsibilities of lawyer-mediators and the limits of mediator intervention. Issued on 15 October 2025, the opinion addresses lawyer-mediators’ duties toward unrepresented parties, requires them to avoid statements implying that they are seeking to achieve a party’s best interests, and applies a broader standard concerning honesty and misleading communications to lawyer-mediators than the standard applicable to lawyers negotiating on behalf of clients. The opinion permits lawyer-mediators to provide truthful information, including legal information and views on how a tribunal may resolve legal or factual questions, but states that they should not tell a party that a proposed settlement is in that party’s best interest.

The ADR article identifies the use of mediator’s proposals as one of the principal areas of disagreement following the opinion. Jeff Kichaven argues that an unvetted mediator’s proposal can require the mediator to make the type of best-interest determination that Opinion 518 prohibits and advocates a model in which the timing and substance of the proposal are discussed with counsel. Other commentary takes a different view, noting that Opinion 518 does not expressly address mediator’s proposals and does not itself establish that only vetted proposals are permissible. The debate therefore centres on the boundary between providing information that enables parties to make their own decisions and substituting the mediator’s judgment for that of the parties.

The ADR article also discusses written mediator’s proposals as a possible approach when parties agree that a proposal may assist after negotiations reach an impasse. It argues that a written proposal can give parties and their advisers additional time to consider proposed terms away from the immediate pressures of the mediation room and allow organisations to assess the proposal internally. The article further discusses mediator proposals in the context of cognitive biases in negotiation and concludes that Opinion 518 reinforces the principles of neutrality, candour and party self-determination while leaving continuing debate over how actively a mediator may assist parties in reaching resolution. Subsequent ABA commentary similarly describes the opinion as having generated considerable discussion within the ADR community, with differing views on its effect on mediation practice.