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A Newton policy is a Rego program that evaluates whether an Intent should be approved. Policies reference data from two sources: configuration parameters (data.params) and runtime data from WASM oracles (data.data).

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What Makes Up a Policy

Every policy deployment requires these files:
FilePurpose
policy.regoRego policy logic — the core evaluation rules
policy.wasmCompiled WASM data oracle (see Writing Data Oracles)
params_schema.jsonJSON Schema defining configurable parameters
policy_metadata.jsonHuman-readable policy metadata
policy_data_metadata.jsonHuman-readable oracle metadata

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Data References

Your Rego policy can access three data namespaces:
PathSourceDescription
inputIntentThe transaction intent being evaluated (from, to, value, data, chain_id, function_signature)
data.paramsPolicyClientConfiguration parameters set by the contract owner (thresholds, allowlists)
data.dataPolicyData WASMRuntime data returned by your WASM oracle (prices, KYC status)

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Your First Policy

Create policy.rego: 
package sanctions_check

default allow := false

# Allow the transaction if the oracle reports no sanctions match
allow if {
    data.data.is_sanctioned == false
}

# Also allow if the sender is on the explicit allowlist
allow if {
    input.from == data.params.admin
}
This policy:
  1. Defaults to deny (allow := false)
  2. Allows transactions where the oracle reports no sanctions match
  3. Always allows transactions from the configured admin address

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Using Intent Fields

The input object contains the Intent fields: 
package spend_limit

default allow := false

# Allow if transfer value is under the configured limit
allow if {
    input.value <= data.params.max_value
}

# Block transfers to specific addresses
deny if {
    input.to == data.params.blocked_address
}

allow if {
    not deny
    input.chain_id == 11155111
}

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Using Oracle Data

The data.data path contains whatever your WASM oracle returned: 
package price_check

default allow := false

# Only allow trades when the price is below the configured maximum
allow if {
    data.data.price < data.params.max_price
    data.data.symbol == "BTC"
}

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Parameter Schema

Create params_schema.json to define which parameters contract owners can configure: 
{
  "type": "object",
  "description": "Sanctions check policy parameters",
  "properties": {
    "admin": {
      "type": "string",
      "description": "Admin address that bypasses sanctions check"
    },
    "max_value": {
      "type": "number",
      "description": "Maximum transfer value in wei"
    }
  }
}
Leave properties empty if your policy has no configurable parameters: 
{
  "type": "object",
  "description": "",
  "properties": {}
}

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Metadata Files

Create policy_metadata.json: 
{
  "name": "Sanctions Check Policy",
  "version": "0.0.1",
  "author": "Your Name",
  "link": "https://github.com/your-org/your-policy",
  "description": "Checks transaction counterparties against sanctions lists"
}
Create policy_data_metadata.json: 
{
  "name": "Sanctions Oracle",
  "version": "0.0.1",
  "author": "Your Name",
  "link": "",
  "description": "Fetches sanctions data from screening API"
}

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Directory Structure

Organize all files into a policy-files/ directory: 
policy-files/
├── policy.rego
├── policy.wasm
├── params_schema.json
├── policy_metadata.json
└── policy_data_metadata.json

cp policy.wasm policy.rego params_schema.json \
   policy_data_metadata.json policy_metadata.json policy-files/

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Testing Locally

Test your policy with the CLI before deploying: 
newton-cli policy simulate \
  --wasm-file policy-files/policy.wasm \
  --rego-file policy-files/policy.rego \
  --intent-json intent.json \
  --entrypoint "sanctions_check.allow" \
  --policy-params-data policy_params.json
The --entrypoint value must match your Rego package name + rule name. For package sanctions_check with rule allow, use sanctions_check.allow.
For a full reference on supported Rego syntax, see the Rego Syntax Guide.

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Next Steps

Deploying with CLI

Deploy your policy to IPFS and register it on-chain

Smart Contract Integration

Integrate the policy into your smart contract