title: How do I return an HTTP 400 - Bad Request error from a web form request?
body: <p>The subject pretty much says it all. I have an EstateReport web form that must be called with an EstateId request parameter. I want to return an appropriate HTTP error if this parameter is not present. How do I return an HTTP error 400 as my response?</p>
  <p>On a tangent, should I return an error if the required parameter isn't present, which I feel is more correct, or redirect to the search page for the report, which is more user friendly?</p>