Let the Jury Decide! Polkamarkets Announces Kleros Court Integration on Polygon for Market Resolution.

Polkamarkets Labs
Polkamarkets Blog
Published in
3 min readNov 7, 2023

Polkamarkets Labs is happy to announce the release of the integration between Polkamarkets and Kleros Court on Polygon. Polkamarkets users can now decide to bypass the bonding escalation process used in market resolution and summon a jury in a Kleros Court to resolve a prediction market.

More robustness, more user choice in market resolution

Polkamarkets has always resolved markets using a crowd-sourced bond escalation mechanism, also known as an Optimistic Oracle system.

In this process, Alice bonds POLK tokens on the outcome that they believe is the correct one. If Bob disagrees with Alice, he can challenge Alice by bonding double the amount of POLK tokens on another outcome. The process goes on until a three-day window lapses without a challenge. If Bob’s were to be the final bond, he’d recoup the bonded POLK and win Alice’s bonded POLK.

This process has worked fantastically so far. Out of the 2670 markets created across all chains and versions of Polkarmets, only twice has the Optimistic Oracle resolved a market incorrectly, amounting to a 99.9% success rate. In both cases, markets were small, and the participants ignored how the resolution process was managed, resulting in a wrongful resolution.

Despite the system’s success, there is a theoretical problem with its design. While the system makes it exponentially more risky to try to cheat the result of the market — a malicious actor stands to lose an exponentially larger amount of bonded POLK with every wrongful bond — it still gives an advantage to users who hold large amounts of POLK. Even though no “bonding war” was ever observed on Polkamarkets, the potential problem exists.

For that reason, Polkamarkets Labs is introducing a fail-safe mechanism that allows any user to bypass the Optimistic Oracle by summoning a Kleros Court so that a jury will impartially decide what the correct outcome of a market is.

Let the jury decide!

Kleros Court has been around since 2019 and has helped settle 1600+ disputes and currently has over 700 active jurors. As a well-known and well-trusted protocol, Kleros Court is an excellent choice for providing an additional layer of robustness to the Polkamarkets Protocol.

To bypass the Optimistic Oracle process in new markets created since Friday, November 3, 2023, Polkamarkets users can click a button in the Polkamarkets Web App to escalate the resolution of a Polygon-based prediction market to a Kleros Court.

After at least one POLK bond has been placed, any Polkamarkets user can “Apply for Arbitration” and let a Kleros Court jury resolve a market.

A Kleros Court currently costs 0.496 ETH to summon. The Kleros protocol uses this amount to pay Jurors for their work and cover operational costs. It’s also expensive enough that it should prevent users from opting into it without good reason.

When a Kleros Court renders its decision, the Polkamarkets Protocol will still give a three-day window for users to appeal the decision should they disagree with the original decision. The same procedure applies: the appealing user pays the fee, the Court renders its decision, a three-day window is open, etc.

How does it work in detail?

Check out the Arbitration with Kleros article on the Polkamarkets Documentation to understand how the process works from the Polkamarkets side. Note again that this feature is only available on Polygon and for markets created on or after Friday, November 3, 2023.

To learn more about how Kleros Courts work — how jurors are selected, how they deliberate, how to submit evidence, etc. — check out the documentation and explainer videos available on the Kleros Court website.

About Polkamarkets

Polkamarkets is a Web3 Prediction Markets Protocol built with open-source technology. Polkamarkets enables user-friendly, transparent and secure prediction markets and can be tailored to the specific needs of anyone.

About Kleros

Kleros is an open-source online dispute resolution protocol which uses blockchain and crowdsourcing to fairly adjudicate disputes. Development efforts are coordinated by Coopérative Kleros, a Société Coopérative d’Intérêt Collectif (SCIC) incorporated in France. All of Kleros’ research and code development are open source and free for anyone to use.