In response to your question, it's the case law that has accumulated on the subject and has been confirmed, in certain cases, by the superior courts. I'll cite a specific example: when an individual who is not happy with a decision or recommendation files exactly the same request the following week and repeats it systematically, that corresponds to a frivolous request. It's quite complicated to define that in legal terms. It's a matter of both case law and common sense.
On May 15th, 2008. See this statement in context.