How can you demonstrate or cite “Chilling effects” when quashing subpoenas? Perhaps every reporter needs to ask every unnamed source if they would be talking if they thought the reporter wouldn’t protect their identity as a pro forma question, and then someone needs to compile all of the john and jane Doe (1-9999) results.
Besides quantifying the results of numerous off the record sources, if the question were the pro forma start of every unnamed source interview, then individual reporters could also explicitly and honestly state that the source would not be talking without protection, and back that up with a quote.
Yes, there are arguments to be made from casebooks. But there is also data to gather and present showing how legal rules affect the flow of news to the public. In Google’s “right to be forgotten” case, that means cataloguing the take-down requests it receives. Over a period of years, a picture will emerge of knowledge the public can no longer easily access on the Internet because of the European Union’s ruling on the issue.
For reporters and editors seeking to prove the existence of a chilling effect, the challenges are in many ways more daunting because they are trying to demonstrate not what has been lost but what will not be published in the first place.
A methodological knot thus lies at the heart of this project
More: Press Subpoenas Are a Bigger Problem Than You’d Think : Columbia Journalism Review