Send a 400 error response code in Jax ws soap service

So I have a Jax ws soap service in which I have to send an error code 400 in http response if the validation of the xml input received fails. But whatever exception I try to throw from the service it ends up throwing an error code of 500. I tried sending a BadRequestException from the web service but it also sends a 500 internal server error response code to the calling service. So is there any way I can achieve that?