[ebrenes]

And why not just make it clear that valid_data depends on valid_user?

    valid_user = loggedIn() && hasRole(ROLE_ADMIN)
    valid_data = valid_user && data != null && validate(data)

    if (valid_user && valid_data) …

I think this makes it clear that valid_data has a dependency on valid_user that was being hidden in the previous version, which we're now making clear. It will look a bit weird, but I think that's a positive because it draws attention to the fact that the short-circuiting is required and that double-look coupled with a short comment will make everything much more readable. The previous version does not convey as much meaning, in my opinion.

    if (loggedIn() && hasRole(ROLE_ADMIN) &&
        data != null && validate(data)) …