# IAM JSON policy elements: Effect
Effect

The `Effect` element is required and specifies whether the statement results in an allow or an explicit deny. Valid values for `Effect` are `Allow` and `Deny`. The `Effect` value is case sensitive. 

```
"Effect":"Allow"
```

By default, access to resources is denied. To allow access to a resource, you must set the `Effect` element to `Allow`. To override an allow (for example, to override an allow that is otherwise in force), you set the `Effect` element to `Deny`. For more information, see [Policy evaluation logic](reference_policies_evaluation-logic.md).