The Daily Kos has a diary discussing the Sarah Olson [3] case, with lots of good debate in the comments section (including a couple of comments by me).

As the discussion illustrates, there are still some people (including people who oppose the war in Iraq) who do not understand the importance of Sarah Olson [4]'s principled stand [5] against testifying in the court-martial of Ehren Watada [6]. This is not a case of a journalist refusing to identify an anonymous source or trying to protect confidential information. It is a case of a soldier who has been put on trial, in part, because he spoke publicly about his opposition to the war. In short, it is a case of a journalist being asked to assist in the prosecution of a soldier's political free speech.

Some people still seem to think that Sarah Olson was merely being asked to "authenticate a document," and that somehow she was obligated to do so. The "document" in this case, however, was her journalistic report of her interview with Ehren Watada, in which he explained how he came to believe that the war in Iraq [7] was wrong and that he had a moral obligation not to participate in it.

As far as I know, there is no other prior example of a journalist in the United States being subpoenaed to authenticate information for the specific purpose of putting someone on trial for their political free speech. That's what was happening here. By "authenticating" her report on Watada's political speech in a military court, Sarah Olson would have been collaborating with the prosecution of it.

What was the nature of Ehren Watada's political speech? He said that Bush had betrayed the public trust and "I believe the whole war is illegal. I'm not just against bearing arms or fighting people. I am against an unjustified war. [8]"

The military considered Watada's words so threatening that they wanted to send him to prison for two years just for speaking them to a reporter. By contrast, military courts have taken no action in response to grotesquely racist statements by other soldiers who have referred to Iraqis as "Hajis" or "sand niggers [9]" or who have written songs that celebrate the killing of Iraqis [10]. I think these expressions of bigotry and homicidal glee do much more to bring discredit upon the military than Watada's principled statement of objection to the Iraq war.

The bottom line is that if you think it's okay to send Watada to prison for speaking his conscience and saying what he thinks, you're probably also comfortable with the idea that a journalist should collaborate by giving testimony against him. If, on the other hand, you think Watada has the right to explain publicly why he refuses to deploy to Iraq, you cannot possibly think that Sarah Olson should have been forced to testify against him.