# LDC-E4705 — A malformed evidence policy declaration

## What it means

An evidence policy declares, in a closed vocabulary, how raw support is
projected and which rules may accept it. A policy with a missing or
repeated item, an unknown profile, an unknown slot, or a name that
resolves to nothing cannot run the phase, and the compiler refuses the
offending item.

Complete the declaration: every policy names its profile, the relation it
accepts, at least one guarded predicate, and at least one rule — each
exactly once, each resolving to something real.

## Example

```law
language "law.core" version "0.2";
package demo.diagnostics version "0.1.0";
namespace "urn:law:demo:diagnostics";

entity Thing;
relation paid(t: Thing) kind empirical;
relation ev_edge(edge: Text, doc: Text, link: Text) kind empirical;
relation accepted_support(edge: Text) kind institutional;
rule Judge strict { for edge: Text; for doc: Text; when ev_edge(edge, doc, "supports"); then accepted_support(edge); }
evidence policy EvpV1 {
accepts accepted_support;
protects paid;
input edge ev_edge;
rule Judge;
}
```

## Fix

```law
language "law.core" version "0.2";
package demo.diagnostics version "0.1.0";
namespace "urn:law:demo:diagnostics";

entity Thing;
relation paid(t: Thing) kind empirical;
relation ev_edge(edge: Text, doc: Text, link: Text) kind empirical;
relation accepted_support(edge: Text) kind institutional;
rule Judge strict { for edge: Text; for doc: Text; when ev_edge(edge, doc, "supports"); then accepted_support(edge); }
evidence policy EvpV1 {
profile "law.core.evidence-policy/0.1";
accepts accepted_support;
protects paid;
input edge ev_edge;
rule Judge;
}
```

## Engine message

The engine reports this in its own wording:

```text
example.law:10:17: error LDC-E4705: evidence policy "EvpV1": required `profile` item is missing (§78.2.1)
```

## Related

- [Facts and evidence](/constructs/facts-and-evidence/) — what an assertion carries.