When Process Becomes the Appeal: Arbitrator Authority, AAA Rules, and “Errors of Law”
Post-award litigation often looks like it is about “who was right,” but the arguments tend to be framed differently: Did the arbitrator have authority to proceed the way the arbitrator did? And if the losing side claims the arbitrator got the law wrong, does that legal issue even qualify for meaningful judicial review?
A February 13, 2026 unpublished decision from the Michigan Court of Appeals, In re Mitchell N. Bunker and Linda K. Bunker Trust, is a useful reminder that these two questions have very different lanes. The court’s analysis shows why arbitrator authority disputes are frequently the most realistic path to vacatur, while “error of law” arguments remain tightly constrained by a deferential standard and a narrow record.
This case arose out of a family trust dispute, but the arbitration lessons translate well to commercial and consumer matters: define the arbitrator’s procedural discretion clearly, document agreements about how the hearing will be conducted, and understand how limited appellate review will be once the award is issued.
Background: a trust dispute that became a procedural challenge
Mitchell and Linda Bunker created a revocable living trust holding several parcels of real estate. Dixie Bunker was named successor trustee and beneficiary; Randolph Bunker was a beneficiary. In June 2021, four “Lady Bird deeds” were created purporting to transfer trust property to Dixie and other grantees. After Linda died in August 2021, Mitchell signed the deeds in September 2021, and Dixie recorded them in October.
A county official later sent a letter explaining that the deeds were invalid as recorded because the property belonged to the trust and the grantor was listed in an individual capacity rather than as trustee. Mitchell died shortly thereafter. Dixie then recorded the deeds again in November 2021, this time with alterations identifying the grantor as the trust or Mitchell as trustee.
Randolph filed a probate action with claims including fraud, undue influence, and duress, and the trust instrument required disputes between trustee and trust parties to be resolved through binding arbitration governed by the AAA Commercial Arbitration Rules and Mediation Procedures. The parties selected an attorney arbitrator.
Crucially, weeks before the arbitrator issued a final written decision, counsel participated in a status conference and signed a written agreement waiving oral testimony and proceeding through written briefs with exhibits, after which the arbitrator would issue a written decision.
The arbitrator ruled for Randolph and concluded, among other things, that the deeds were invalid due to lack of delivery and other defects, and that the parcels remained trust property. After issuing the decision, the arbitrator canceled a later-scheduled arbitration hearing on the ground that the written decision resolved all issues. The probate court affirmed the award and quieted title consistent with it. Dixie appealed.
The main event: arbitrator authority under AAA rules and party agreements
The appellate court treated the “authority” question as a distinct category of review, recognizing that courts may not re-litigate the merits or reweigh facts. That framing matters: a party arguing “the arbitrator exceeded authority” must show something more than disagreement with the outcome. The challenge must identify a genuine procedural overreach that falls outside what the arbitration agreement and governing rules permitted.
Dixie’s authority arguments came in several forms:
1) “No evidentiary hearing happened, so the arbitrator lacked power to issue a final decision”
This is the most common authority-style argument in real life, and it is also one of the easiest to lose when the record reflects party consent or rules-based discretion.
The court focused on AAA Rule 33 (Conduct of Proceedings). The rule requires a fair opportunity to present evidence, but it also gives the arbitrator discretion to vary procedure as long as the parties are treated equally and have the right to be heard. Most importantly, Rule 33 expressly recognizes that the parties may agree to waive an oral hearing.
That was decisive. Counsel signed a written agreement to proceed on briefs and exhibits with no testimony. Both sides had representation, submitted written materials, and neither side was permitted to offer witness testimony. The court emphasized that nothing in the written agreements barred resolution without a hearing, and it rejected the suggestion that Dixie did not “personally” agree, because her attorney agreed in open court and there was no showing of mistake, fraud, or unconscionable advantage tied to that procedural agreement.
Practice takeaway for lawyers: if an arbitration is going to proceed on a paper record, treat that stipulation like a deal document. Make it clear, in writing, whether testimony is waived, what evidence is permitted, what deadlines apply, and what constitutes a “complete” record. Those details often become the entire battlefield later.
2) “The arbitrator could not cancel the scheduled hearing”
The record included a hearing date that would have occurred after the written decision issued. Dixie argued the AAA rules did not permit canceling the hearing.
The appellate court’s response was practical: once the parties agreed to a briefs-only process culminating in a written decision, and the arbitrator concluded the decision resolved all issues, the later scheduled hearing was no longer necessary. Nothing in the cited rules created a requirement that a hearing must occur after a final decision has already been issued on the agreed record.
This is an underappreciated point. Authority challenges sometimes rely on the idea that “something was calendared, so it had to happen.” But arbitration calendars are not statutes. The governing rules and party stipulations usually matter more than the calendar.
3) “The arbitrator should have been disqualified for bias”
Dixie invoked AAA Rule 19 (Disqualification of Arbitrator) but, according to the court, did not support the argument with record facts or legal development. The court treated it as abandoned.
That outcome is not unique. Bias challenges are serious, but courts demand specificity. A generalized complaint that the arbitrator “was not impartial” rarely survives unless tied to actual nondisclosure, conflicts, or conduct that meets the legal standard.
4) “The arbitrator wrongly closed the record and refused more evidence”
Dixie pointed to AAA Rule 40 (Closing of Hearing). The court read Rule 40 together with Rule 33 and held the arbitrator had authority to close the record when satisfied it was complete, and that proceedings close when briefs are filed.
In other words, the record-closing decision was procedural discretion, not a legal error on the face of the award.
5) “The arbitrator relied on improper material, including dismissed criminal charges”
This argument often appears as a backdoor merits appeal: the party claims the arbitrator was “influenced” by something and asks the court to infer the arbitrator’s reasoning.
The court rejected that pathway. Under AAA Rule 35 (Evidence), conformity to legal rules of evidence is not required, parties may offer relevant and material evidence, and the arbitrator decides admissibility, relevance, and materiality. Just as important, the court noted that evaluating the influence of that information would require inquiry into the arbitrator’s mental processes, which is not permitted.
Practice takeaway: if a party believes certain categories of evidence should not be considered, address it early and explicitly, preferably with a procedural order or stipulation. Waiting until after an adverse award and then arguing “the arbitrator must have been influenced” is usually a dead end.
The secondary lane: “errors of law” and why courts rarely bite
After rejecting the authority arguments, the court turned to claimed legal errors. The opinion underscores a principle that parties sometimes forget when they draft appellate briefs: even when a court is allowed to review legal error, the review is still narrow, and the error must be apparent on the face of the award and material to the result.
Here, Dixie argued that Michigan recording laws were violated, that the trust terms permitted changes, and that the deeds validly transferred the parcels before Mitchell died. The court concluded these arguments did not show a clear, material legal error warranting judicial correction.
Why? Because the arbitrator’s decision rested heavily on factual findings, including findings about intent and delivery. Under Michigan law, delivery is essential to pass title and whether delivery occurred is a factual question. The arbitrator found the evidence did not show the required intent and concluded delivery never occurred. Once the arbitrator made those factual determinations, the court treated them as binding and declined to re-litigate them under the guise of “legal error.”
The court also noted that Dixie’s fraud and duress arguments were not meaningfully developed and, in any event, the arbitration decision did not address fraud, duress, or undue influence in a way that established reversible legal error on the face of the award.
Bottom line: the “question of law” lane is real, but it is narrow. In many arbitration appeals, the legal arguments collapse because they ultimately depend on reweighing facts, disputing credibility, or speculating about the arbitrator’s reasoning.
What this decision means for counsel and parties
This case provides a clean, practical set of reminders for attorneys managing arbitration strategically:
Procedural agreements are powerful. A written stipulation to waive testimony and proceed on briefs can be outcome-determinative on review. Treat it as a high-stakes document, not an administrative convenience.
Arbitrator authority challenges must be genuinely procedural. Courts are alert to “exceeded authority” arguments that are really merits appeals in disguise.
If the rule grants discretion, assume the court will enforce it. Rules on evidence, record-closing, and case management often give arbitrators broad latitude.
Legal-error review is not a second trial. If the claimed “law issue” depends on factual disputes, the odds of vacatur drop sharply.
Build the record you will need later. If an issue truly implicates authority (waiver validity, hearing rights, equal treatment, disclosures), make it explicit and preserve it properly during the arbitration, not after.
A final thought for parties choosing a neutral
When arbitration turns into post-award litigation, the dispute often shifts from “who is right” to “whether the process was fair and authorized.” That is precisely why selecting a neutral who is disciplined about procedure, transparent about process choices, and careful about party agreements can reduce downstream risk.
Nationwide ADR® is built for that reality. With a national practice focused on arbitration and mediation — and additional support through early dispute resolution strategies, early neutral evaluation, mock trials, and mini trials — Nationwide ADR helps counsel and clients resolve demanding cases with process clarity and credibility. Trusted. Balanced. Resolution Driven. For matters where the line between procedural discretion and “exceeding authority” may later be tested, thoughtful process design at the outset is often the best investment a party can make.