The Constitution merely protects the freedom of speech and publication — not the freedom to keep secrets, which is what journalists are asking for when they seek special privileges of non-disclosure. Increasingly, journalists seem to be focusing on what not to tell us. In doing so, they're usually pursuing their own interests, not the First Amendment's or their readers'.The idea of journalistic confidentiality is ludicrous. While a writer can promise to keep a person's name out of the newspaper, the journalist has no ability to make the same promise about any other aspect of life--particularly the courts. There is no particular public policy served by journalist sheild laws. The idea of attorney/client privilege, doctor/patient privilege or other types of recognized privileges is that they stem from constitutional rights guaranteed to individuals and necessary for the trust and confidence of those individuals.
The other problem with journalist "shield" laws is that journalism isn't a profession; it's an activity, one now engaged in by many. With the proliferation of blogs, podcasts, YouTube videos and the like, anyone can be a journalist. But if anyone could assert a journalistic privilege not to disclose sources, the work of the courts would be far tougher.
Efforts to limit the privilege to "professional" journalists, on the other hand, quickly transform into a sort of guild or licensing system for the press — ironically, something that the First Amendment clearly prohibits.
Complying with subpoenas might make journalists' lives more difficult, but lots of industries are burdened by having to comply with the law.
Journalists usually aren't terribly sympathetic to those industries' complaints. We should be no more sympathetic to reporters' special pleading.
A journalist sheild law serves no personal interest. The freedom of the press means the govenrment cannot censor the newspaper or prevent publication. It does not mean that the inidividuals who contribute to the press (the writers or their sources) have any special status because of their connection to the press.