<p>Is it possble to have something like this in ASP.NET MVC...</p>

<pre><code>[Authorize]
[AcceptVerbs(HttpVerbs.Get)]
public string AddData(string Issues, string LabelGUID)
{
    return "Authorized";
}

[AcceptVerbs(HttpVerbs.Get)]
public string AddData()
{
    return "Not Authorized";
}
</code></pre>

<p>So if the user is not logged in, it defaults to the un-Authorized action.</p>

I don't believe so. The controller action with the best parameter match will get selected and then the attributes will be applied.
You could use
```
```
if (Request.IsAuthenticated)
{  
    return "Authorized";
}
else
{  
    return "Not Authorized";
}
```
```
Under the hood [Authorize] is essentially doing the same thing
```
```
protected virtual bool AuthorizeCore(IPrincipal user)
{
    if (user == null)
    {
        throw new ArgumentNullException("user");
    }

    if (!user.Identity.IsAuthenticated)
    {
        return false;
    }

    ...snip...
}
```
```