Trucking: billing for freight, commercial transaction, oppinion

Question
I have always understood that when a supplier sends goods to a customer via common carrier, the cost from the carrier could not be marked up by the supplier when billing the customer.  Is this true?  If so, where do I find it in writing?

I have been told this for years, but have never seen it in writing.  I was taught freight costs passed through at cost and could not be marked up.

Answer
John, this is a commercial transaction that is negotiable between the the seller and buyer.  There may be common business practice in different industries but no regulation to dictate this part of the agreement between seller and buyer.  There was a theory before deregulation that what you described was considered unlicensed brokerage but I don't know if it was ever prosecuted and pretty much sure the courts would reject that idea now.  Just my oppinion, but you check with legal council if you have a case.
Jim