JSON that has { }, [ ], field:value <- Well Formed no Business Rules If a add a JSON Schema, and the document follows that Schema <- Valid I have program to produce JSON (REST Web Service) before I send this JSON document out... I call a Validater (I pass the Schema, and the document) I should not sanitize it I am writing a REST Client, I expect a JSON document as input I will take the document, and validate it before I use it.