I have a WebApi ModelBinder that's used to convert from a string in a url to an object representing what segment of a website a client is requesting. Clients only have access to certain website segments.

Can I handle authorization from the ModelBinder? Right now I'm doing this which does return a 401; however, the Api controller code still gets executed.

```
class SegmentModelBinder : IModelBinder
{
    public bool BindModel(HttpActionContext actionContext, ModelBindingContext bindingContext)
    {
        var value = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
        if (value == null || String.IsNullOrEmpty(value.AttemptedValue))
            return false;

        if (/*doesn't have access*/)
            actionContext.Response = new System.Net.Http.HttpResponseMessage(System.Net.HttpStatusCode.Unauthorized);
        else
            bindingContext.Model = /*set object*/;

        return true;
    }
}

```

How can I respond with a 401, and also end the execution of the request at that point?