To answer your question in short, NO!! No one can cite that law , as it does not exist. In fact, it is a buyer's agent's responsibility to assist you in deciding what to offer, based on tools such as Market Analysis, Taxable Values, recent sales, and of course, their own knowledge of the community.
Myself, I first ask my clients if they simply want to offer( in hopes of snagging a great deal) or do they really want that home and want to BUY it. The offers will differ, both in price and terms structure.
Either way, if you EVER fail to get a direct, honest answer from your Realtor, find another