How UIM Arbitration Works in Washington
If you’ve been hurt by a driver who didn’t carry enough insurance, you may turn to your own underinsured motorist (UIM) coverage — and somewhere along the way, someone might mention “arbitration.” That word causes confusion, because Washington has two very different processes that both get called arbitration, and people often assume one works like the other. This post walks through where UIM arbitration comes from, what it decides, and why it isn’t the same animal as Washington’s mandatory civil arbitration.
Disclaimer: This post is intended for general informational purposes only and does not constitute legal advice. For guidance specific to your situation, please consult with a qualified personal injury attorney.
Where UIM Arbitration Comes From: Your Own Policy
The first thing to understand is that UIM arbitration is contractual. It doesn’t come from a court rule — it comes from the language of your own auto policy. Because a UIM claim is a claim against your own insurer, that policy’s terms govern how a dispute gets resolved, and some policies include an arbitration provision for exactly that purpose.
Here’s the catch: not every policy has one. Some UIM policies contain an arbitration clause; others may not, in which case a dispute might be resolved a different way. Because it all depends on the contract, the first step is reading the policy — the UIM provisions and any separate arbitration agreement — rather than assuming arbitration is either available or required.
What UIM Arbitration Tends to Decide
Because the process is defined by the policy, what an arbitration resolves depends on that policy’s language. That said, UIM arbitration provisions commonly focus on two questions: whether the insured is legally entitled to recover from the underinsured driver, and the amount of the damages. In plain terms, the arbitrator often decides the same core issues a jury might — was the other driver at fault, and what is the injured person’s harm worth. But that’s a general pattern, not a fixed rule; the issues submitted are whatever the policy and any arbitration agreement say they are.
The Ground Rules Depend on the Contract
This is where UIM arbitration surprises people. Unlike a court proceeding, where a public set of rules applies to everyone, the ground rules for UIM arbitration are largely set by the policy and any arbitration agreement the parties sign. Depending on that language, the process may address:
- Arbitrator selection — how many arbitrators there are and how they’re chosen.
- Discovery — what information the parties can exchange beforehand, and how much.
- Rules of evidence — whether formal courtroom rules apply, and how testimony or reports come in.
- Who pays the fees — how the arbitrator’s fees and the costs of the proceeding are divided.
- Appeal rights and finality — whether the result is binding, and what a party can do if they disagree with it.
All of these can differ a great deal from one policy to the next, and sharply from how a court-connected arbitration runs. That’s the practical reason to read the policy carefully — and, ideally, have someone help you understand what a particular clause commits you to.
Not the Same as Washington’s Civil (Mandatory) Arbitration
Here’s the distinction that trips people up most. Washington also has a court-connected civil arbitration program, governed by the Superior Court Civil Arbitration Rules (SCCAR) — a completely different process from UIM arbitration. It’s part of the court system, governed by court rules rather than a private contract, and it follows a standardized procedure that’s the same regardless of whose case it is. Critically, a party dissatisfied with the arbitrator’s award generally has the right to request a trial de novo — a fresh trial in superior court — within a short deadline after the award is filed. We cover that program in our practical guide to Washington’s civil (mandatory) arbitration, and it’s a useful contrast here precisely because it works so differently.
UIM arbitration, by comparison, comes from your policy, not the court’s rules; its procedures are whatever the contract sets; and whether the result is binding — and whether anything like a trial de novo exists — depends on that contract rather than on SCCAR. So if you’ve read about civil arbitration’s trial-de-novo safety valve, don’t assume those features carry over. They’re two separate roads.
A Quick Word on UIM Coverage Itself
It helps to keep the coverage in view too. UIM may compensate you for damages that exceed the liability limits available from the at-fault driver — up to your own UIM limit and subject to your policy’s terms. It doesn’t simply “stack” dollar-for-dollar on the other driver’s policy; the amount turns on your total damages, the applicable limits, and your policy’s provisions, and Washington permits anti-stacking provisions that can limit coverage to the highest single applicable limit rather than adding limits together. For the fuller picture, see our post on uninsured and underinsured motorist coverage in Washington.
Final Thoughts
The key takeaway is simple: UIM arbitration and Washington’s civil (mandatory) arbitration are two different processes that happen to share a name. UIM arbitration is a creature of your own policy, so its availability and its ground rules depend on what your contract says — which is why reading the policy is the right starting point. Court-connected civil arbitration, by contrast, runs on court rules and comes with a trial-de-novo right. Knowing which one you’re facing keeps you from carrying the wrong expectations into it.
If you’re facing a UIM claim and trying to make sense of an arbitration clause in your policy — or you just want to know which kind of arbitration you’re looking at — we’re glad to help. Reach out to schedule a consultation, and we’ll walk through your coverage and your options. We help injured people throughout Washington understand the coverage available to them.
