> ## Documentation Index
> Fetch the complete documentation index at: https://kleros.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# KlerosCore

> Core arbitrator contract disputes, appeals, juror management, rulings

Central arbitrator contract of Kleros V2. Manages dispute creation, juror drawing, period transitions, appeals, and ruling execution.

**Version**: 0.10.0 | **Proxy**: UUPS Upgradeable

## Key Methods

### `createDispute(uint256 _numberOfChoices, bytes _extraData) payable → uint256`

Creates a new dispute. Caller must send sufficient ETH (or approved ERC-20) for arbitration cost. The `extraData` encodes the target `courtID` (as `uint96`) and `minJurors` (as `uint256`).

### `arbitrationCost(bytes _extraData) view → uint256`

Returns current arbitration fee (in ETH) for the specified court/juror configuration.

### `appeal(uint256 _disputeID, uint256 _numberOfChoices, bytes _extraData) payable`

Handles appeals including court jumps and dispute kit jumps.

### `execute(uint256 _disputeID, uint256 _round, uint256 _iterations)`

Distributes PNK stakes and fees to jurors based on vote coherence.

### `executeRuling(uint256 _disputeID)`

Finalizes dispute and calls `rule()` on the Arbitrable contract.

### `currentRuling(uint256 _disputeID) view → (uint256 ruling, bool tied, bool overridden)`

Returns the current ruling and its status:

| Return       | Type      | Description                                                                                                                                                                                                |
| ------------ | --------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `ruling`     | `uint256` | Current winning option. `0` means "Refuse to Arbitrate" or no majority yet.                                                                                                                                |
| `tied`       | `bool`    | `true` when two or more options have equal votes. A tied dispute will default to ruling `0` if the appeal period expires without resolution. Always design your contracts to handle ruling `0` explicitly. |
| `overridden` | `bool`    | `true` when the parent court changed the ruling on appeal. Useful for monitoring or analytics — the final `rule()` callback on your arbitrable contract already reflects the overridden value.             |

### `setStake(uint96 _courtID, uint256 _newStake)`

Juror staking — requires prior PNK approval. In the Neo deployment, staking also requires the juror to hold the `KlerosV2NeoEarlyUser` NFT.

## Initialization Parameters

The contract is initialized with the following key parameters (relevant for integrators and governance proposals):

| Parameter                 | Description                                                                       |
| ------------------------- | --------------------------------------------------------------------------------- |
| `_governor`               | Address with full governance rights (pause, upgrade, parameter changes)           |
| `_guardian`               | Emergency address — can pause only                                                |
| `_pinakion`               | PNK token contract address                                                        |
| `_jurorProsecutionModule` | Address authorized to trigger juror penalty execution outside normal dispute flow |
| `_disputeKit`             | Initial dispute kit registered on the root court                                  |
| `_sortitionModuleAddress` | SortitionModule contract address                                                  |
| `_wNative`                | Wrapped native token address (WETH on Arbitrum) — used for ERC-20 fee conversions |

## Governance Roles

* **Governor** Pause/unpause, change parameters, upgrade, change roles
* **Guardian** Can only pause (emergency response)

When paused: staking and rewards blocked. Dispute creation, voting, and appeals continue.

## ERC-20 Fee Support

V2 supports paying arbitration fees in accepted ERC-20 tokens (e.g., WETH, DAI) in addition to ETH:

```solidity theme={null}
// Pay arbitration fees with ERC-20
IERC20 feeToken = IERC20(wethAddress);
uint256 cost = arbitrator.arbitrationCost(extraData, feeToken);
feeToken.approve(address(arbitrator), cost);
arbitrator.createDispute(choices, extraData, feeToken, cost);
```

<Warning>
  ERC-20 fee support is only available when interacting directly with KlerosCore on Arbitrum. The `ForeignGateway` (used for cross-chain arbitration from Ethereum/Gnosis) does **not** support ERC-20 fees — only ETH is accepted through the gateway.
</Warning>

## Dispute Kits

The General Court supports all four dispute kits. The active kit is selected via `extraData` at dispute creation. Current kits on Arbitrum One:

| Kit ID | Name                   | Description                           |
| ------ | ---------------------- | ------------------------------------- |
| 1      | DisputeKitClassic      | Standard plurality voting             |
| 2      | DisputeKitShutter      | Commit-reveal with Shutter encryption |
| 3      | DisputeKitGated        | Gated by eligibility token (SBT)      |
| 4      | DisputeKitGatedShutter | Gated + Shutter commit-reveal         |

## Events

| Event              | Description                       |
| ------------------ | --------------------------------- |
| `DisputeCreation`  | New dispute created               |
| `AppealDecision`   | Dispute appealed                  |
| `CourtJump`        | Dispute escalated to parent court |
| `Ruling`           | Final ruling executed             |
| `TokenAndETHShift` | Reward/penalty applied to juror   |

[View Source](https://github.com/kleros/kleros-v2/blob/master/contracts/src/arbitration/KlerosCore.sol)