# Propagation policies

When you save privacy preferences through the [Consent API (v3)](/content/docs/consent/reference/consent-api-v3/index.html), you can apply a **propagation policy** to automatically extend a user's consent choice across related [privacy notices](/content/docs/consent/guides/privacy-notices/index.html). This page explains how notice hierarchies work and describes each available policy.

## Notice hierarchies [Permalink for this section](/content/docs/consent/reference/propagation-policies#notice-hierarchies/index.html)

Privacy notices in Fides can be organized into parent-child hierarchies. A parent notice represents a broad data-use category, while child notices represent more specific uses within that category.

For example:

```
Marketing (parent)
├── Email marketing (child)
├── SMS marketing (child)
└── Targeted advertising (child)
```

These hierarchies let you group related notices so that consent choices can be managed at different levels of specificity. Without a propagation policy, each notice in the hierarchy is independent -- a user would need to submit a separate preference for every notice in the tree.

## What propagation policies do [Permalink for this section](/content/docs/consent/reference/propagation-policies#what-propagation-policies-do/index.html)

A propagation policy defines rules for how a consent choice on one notice flows to related notices in the same hierarchy. When a policy is active and a user submits a preference, Fides automatically generates additional preferences for parent or child notices based on the policy's rules.

These **policy-generated preferences** are stored alongside the user's explicit choices and are distinguishable through their [per-preference metadata](/content/docs/consent/reference/consent-api-v3#per-preference-metadata/index.html). When a preference is generated by a propagation policy, Fides sets the following fields in the preference's `meta.fides` object:

| Field | Value | Description |
| --- | --- | --- |
| `preference_type` | `policy` | Indicates the preference was generated by a propagation policy (as opposed to `explicit` for user-submitted or `default` for system-generated defaults). |
| `policy_key` | e.g., `cascade_down_opt_out` | The key of the propagation policy that created the preference. |
| `source_preference.notice_key` | e.g., `marketing` | The notice key of the explicit preference that triggered propagation. |
| `source_preference.notice_history_id` | e.g., `pri_notice-history-abc-123` | The notice history ID of the explicit preference that triggered propagation. |

This gives you a complete audit trail: for any policy-generated preference, you can trace it back to the exact user choice and policy that created it.

## Available policies [Permalink for this section](/content/docs/consent/reference/propagation-policies#available-policies/index.html)

Fides provides five propagation policies. The table below summarizes the direction each policy propagates choices:

| Policy | Downward | Upward | Default |
| --- | --- | --- | --- |
| [`cascade_down_opt_out`](/content/docs/consent/reference/propagation-policies#cascade_down_opt_out/index.html) | Opt-out only | No | Yes |
| [`cascade_down_all`](/content/docs/consent/reference/propagation-policies#cascade_down_all/index.html) | All choices | No | No |
| [`cascade_up_all`](/content/docs/consent/reference/propagation-policies#cascade_up_all/index.html) | No | All choices (unanimous) | No |
| [`cascade_up_all_cascade_down_all`](/content/docs/consent/reference/propagation-policies#cascade_up_all_cascade_down_all/index.html) | All choices | All choices (unanimous) | No |
| [`cascade_down_all_cascade_up_opt_in_all_opt_out_conservative`](/content/docs/consent/reference/propagation-policies#cascade_down_all_cascade_up_opt_in_all_opt_out_conservative/index.html) | All choices | Opt-in: any child / Opt-out: all children | No |

### `cascade_down_opt_out` [Permalink for this section](/content/docs/consent/reference/propagation-policies#cascade_down_opt_out/index.html)

This is the default policy when no `policy` parameter is specified.

When a user opts out of a parent notice, that opt-out is applied to all descendant notices. Opt-in choices are **not** cascaded -- only opt-outs flow downward. Nothing propagates upward to parent notices.

**Best for**: Ensuring that opting out of a category opts the user out of everything beneath it, without letting a parent opt-in override individual child choices.

### `cascade_down_all` [Permalink for this section](/content/docs/consent/reference/propagation-policies#cascade_down_all/index.html)

Any choice (opt-in, opt-out, or acknowledge) on a notice is applied to all descendant notices. Nothing flows upward.

**Best for**: Scenarios where a parent choice should be authoritative for everything underneath it.

### `cascade_up_all` [Permalink for this section](/content/docs/consent/reference/propagation-policies#cascade_up_all/index.html)

Child choices roll up to ancestor notices. For a parent's value to be derived from its children, all children must agree. If children have conflicting values, the request is rejected.

**Best for**: Cases where a parent should reflect the unanimous choice of its children. For example, if a user opts out of every child notice, the parent also shows as opted out.

### `cascade_up_all_cascade_down_all` [Permalink for this section](/content/docs/consent/reference/propagation-policies#cascade_up_all_cascade_down_all/index.html)

Combines both directions: explicit choices cascade down to all descendants, and child choices roll up to ancestors using the same unanimity rule as `cascade_up_all`. Setting one child does not force unrelated siblings to change.

**Best for**: Full parent-child consistency without unexpected side effects on sibling notices.

### `cascade_down_all_cascade_up_opt_in_all_opt_out_conservative` [Permalink for this section](/content/docs/consent/reference/propagation-policies#cascade_down_all_cascade_up_opt_in_all_opt_out_conservative/index.html)

Explicit choices cascade down to all descendants. Choices also cascade upward with separate rules for opt-in and opt-out:

- **Opt-in cascades up aggressively**: if **any** child is opted in, the parent is opted in.
- **Opt-out cascades up conservatively**: the parent is only opted out when **all** children (including previously saved and default preferences) are opted out.

If a child opts out but other children remain opted in, the parent stays unchanged.

**Best for**: Scenarios where opt-in should take priority at the parent level. The parent only shows as opted out when everything beneath it is opted out.

## Specifying a policy [Permalink for this section](/content/docs/consent/reference/propagation-policies#specifying-a-policy/index.html)

Pass the `policy` query parameter when calling the [save preferences](/content/docs/consent/reference/consent-api-v3#save-preferences/index.html) endpoint:

```
curl -X POST 'http://localhost:8080/api/v3/privacy-preferences?policy=cascade_down_all' \
  -H 'Authorization: Bearer <access_token>' \
  -H 'Content-Type: application/json' \
  -d '{
    "identity": {
      "email": { "value": "user@example.com" }
    },
    "preferences": [\
      {\
        "notice_key": "marketing",\
        "notice_history_id": "pri_notice-history-abc-123",\
        "value": "opt_out"\
      }\
    ]
  }'
```

In this example, using `cascade_down_all`, the opt-out for the "marketing" notice is automatically applied to all of its descendant notices (such as "email_marketing" and "sms_marketing").

If you omit the `policy` parameter, Fides applies `cascade_down_opt_out` by default.

[Consent API (v3)](/content/docs/consent/reference/consent-api-v3 "Consent API (v3/index.html)") [Mobile SDK](/content/docs/consent/reference/mobile-sdk "Mobile SDK"/index.html)