Statements of Proof and Arbitration Briefs: How Evidence Is Presented
In a civil arbitration, most of the case is decided on paper. There is no long parade of live witnesses the way you might picture at a trial. Instead, the evidence arrives in two written submissions with different jobs and different deadlines: the pre-hearing statement of proof and, sometimes, an arbitration brief. Understanding what each one does helps demystify how an arbitrator actually gets the information needed to rule.
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.
The Pre-Hearing Statement of Proof
The statement of proof is the main event. Under the statewide rule, it is due at least 14 days before the hearing, and it is your side’s comprehensive submission of evidence. In practical terms, almost everything you intend to rely on at the hearing should live somewhere in this package.
This is possible because the arbitration rules specifically permit documentary evidence and signed expert reports or declarations to be submitted in place of live testimony. A doctor does not have to appear in person to explain a diagnosis if a signed declaration says the same thing. That single feature is why the written package can carry the weight of the entire case.
It typically has two parts. The first is the statement itself — a narrative that tells the arbitrator whether liability is disputed, what you are asking for, how the collision happened, what injuries and treatment followed, and which claims are being made. Much of this reads like a tightened version of a well-written demand letter. The second part is the attachments: the actual evidence the narrative points to.
What Goes Into the Attachments
The attachments are where the proof lives. In a typical injury case they may include:
- Declarations from treating physicians, often with the underlying medical records attached as exhibits.
- Wage-loss and other damage declarations.
- Statements from “before and after” witnesses who can describe how you have changed.
- An itemization of medical expenses and receipts for out-of-pocket costs.
- Property-damage documentation and photographs where the damage is significant enough to be worth showing.
The court rule that governs these statements also calls for including certain case documents, such as the complaint, the answer, and a cost bill. In an underinsured-motorist case, the package may also include items unique to that claim, like the policy declarations page or a record of what personal injury protection has paid.
A well-built statement is organized so things are easy to find. Many attorneys number every page of the whole package so anyone can say “page 250 of the plaintiff’s submission” and everyone lands in the same place. A common approach is to letter the exhibits to the statement (A, B, C) while numbering the exhibits attached to a doctor’s declaration (1, 2, 3), which avoids the confusion of nesting numbers inside numbers.
Two Jobs: Get It In, and Be Persuasive
The statement of proof does two things at once. The bare-minimum job is simply to put the evidence in front of the arbitrator. But a strong statement also makes the case — it puts the most important issues front and center rather than burying them. If the central question is, say, whether an injury is likely to be permanent, the statement should say so clearly rather than leaving the arbitrator to piece it together. Getting the evidence in is required; framing it clearly is what makes it effective.
The Arbitration Brief
Because the statements of proof are usually exchanged at the same time, you often do not see the other side’s evidence until you submit your own. That is where the arbitration brief comes in. It can be submitted as late as one day before the hearing, and its purpose is to respond: to raise objections to the defense’s submission, make additional legal arguments, or ask the arbitrator to exclude a particular expert.
For example, if the defense’s statement reveals a doctor you did not expect, the arbitration brief is the place to lay out, in writing, why that opinion should carry little weight — or a motion asking that it be excluded. Arbitrators often find it helpful to have this argument on paper in advance, so they can follow along at the hearing and revisit it afterward rather than relying on notes.
In practice, an arbitration brief is not filed in every case — many cases are handled entirely through the statement of proof and the hearing. When there is genuinely new material to add or a defense witness to respond to, the brief is the right vehicle. And if you happen to receive the other side’s statement before yours is due, some of that responsive material can simply go into your statement of proof instead.
Final Thoughts
The statement of proof carries the weight of an arbitration: it is where your evidence goes, it is due at least 14 days before the hearing, and it deserves to be organized and framed with care. The arbitration brief is the follow-up tool for responding to what the other side puts forward. Together they explain why so much of an arbitration turns on the quality of the paperwork.
If you want to understand how your evidence will be presented in arbitration, we are glad to help. Reach out to schedule a consultation. Our firm works with injured people across Washington State.
