Facebook refused to comply with the subpoena (at a cost of $200/day) on the grounds that it would invalidate the privacy agreement on the site, that they were protected by federal statutes prohibiting information release, and on the principal that the site is "built on trust" and to give in to the subpoena would undermine the site's basis.
The Deputy Commissioner, Randolph Tabb, agreed with Facebook on the grounds that the Federal Electronic Communications Privacy Act protected the member's of the site and that their information was not able to be attained through subpoena.
With technology and social media becoming ever present in our lives it's interesting to see how the courts adjust to the changes and advances. In this case the claimant went ahead and allowed access to her info anyway, but anyone who doesn't want to is now protected. Here's a link to the article on Facebook defeating the subpoena .