How can I return a custom HTTP status code from a WCF REST method?
Solution 1:
There is a WebOperationContext that you can access and it has a OutgoingResponse property of type OutgoingWebResponseContext which has a StatusCode property that can be set.
WebOperationContext ctx = WebOperationContext.Current;
ctx.OutgoingResponse.StatusCode = System.Net.HttpStatusCode.OK;
Solution 2:
If you need to return a reason body then have a look at WebFaultException
For example
throw new WebFaultException<string>("Bar wasn't Foo'd", HttpStatusCode.BadRequest );