(That eternal conflict between First and Sixth Amendments)
It seems the Press has always gotten into a certain amount of hot water where the subject of sources comes up. We all remember the Judith Miller/Marc Cooper fracas that took place some years back.
There was a precedent though - certainly not the first one, but one of the more prominent. The infamous Dr. X Trial of 1978 and the notes of New York Times reporter Myron Farber and the murder trial of Dr. Mario Jascalevich, accused to killing five patients in 1966. It was Farbers New York Times investigative pieces that brought Jascalavich to trial and it was the notes and sources of Farber that put Farber in jail for contempt. The whole question of confidentiality and protection of sources came to light and it was an argument that wound up going all the way to the Supreme Court.
In the end, SCOTUS ruled against the prosecutions argument, but Jascalevich wound up acquitted anyway (lack of evidence).
But it did serve as a reminder how fragile the Amendments are. Here is a commentary delivered by CBS News correspondent and anchor Dallas Townsend from August 17,1978.