And just in case you think my mediation advocacy malpractice series is picking on attorneys, here is ADR Professor Michael Moffitt's excellent article from the Harvard Negotiation Law Review, Ten Ways to Get Sued:  A Guide for Mediators (.pdf).  Here are the ten ways.  For an exhaustive analysis of each, read Moffitt's article.

1. Fail to Disclose a Conflict of Interest
2. Breach a Specific Contractual Promise Regarding Structure or Outcome
3. Engage in the Practice of Law
4. Engage in the Practice of Law Badly
5. Breach Confidentiality Externally
6. Breach Confidentiality Internally
7. Maintain Confidentiality Inappropriately
8. Advertise Falsely
9. Inflict Emotional Distress on a Disputant
10. Commit Fraud

There's also a (disturbing) "head's up" note in a 2006 BYU Law Review "Comment" that mediators may eventually be open to lawsuits for breach of quasi-fiduciary duties.  Despite noting the antipathy in the legal and mediation community in the past for imposing fiduciary duties to the parties, the Comment concludes by predicting that:

mediators may likely owe some level of fiduciary obligations to the parties in certain mediation proceedings--primarily fairness, impartiality, confidentiality, disclosure of conflicts of interest, good faith, and no false misrepresentation. This knowledge allows mediators to prepare for the trends of the near future, when mediation will likely take an established place among the professions, with the accompanying benefits and liabilities of such a position.

THE WRITING ON THE WALL: THE POTENTIAL LIABILITY OF MEDIATORS AS FIDUCIARIES, 2006 BYU Law Review 1033.