Kristy Brewer (J.D. 2005, Miami) has published Tax Shelter Information and How the Confidentiality Rule Protects Clients:  The Relevance of Recent Changes to ABA Model Rule of Professional Conduct 1.6, 13 U. Miami Bus. L. Rev. 31 (2004).  Here is part of the Introduction:

This article analyzes the conflict between the manner in which regulations impose an implicit duty upon lawyers to protect the integrity of the federal income tax system while the profession imposes duties upon lawyers to protect client interests and information. Conflicts arise when client interests are not aligned with the interests of the tax system, which is perhaps the norm rather than the exception. The legal profession operates in a self-regulated fashion by adopting Model Rules or Model Codes that outline the boundaries of lawyering. Tax lawyers have historically argued that tax shelter information is protected under Rule 1.6 of the Model Rules of Professional Conduct, entitled "Confidentiality of Information." Nevertheless, the ABA House of Delegates debated the possibility of amending Rule 1.6 to include permissive disclosures for fraud that creates financial injury. During their Annual Meeting in August 2003, the House of Delegates decided to pass amendments to Rule 1.6 to broaden the scope of permissive disclosure for fraud. Arguably these changes were adopted to hold attorneys more accountable to third parties when clients engage in crimes or frauds that are likely to financially injure those third parties. The changes to Rule 1.6 mark a drastic shift in how tax lawyers’ conflicting interests (tax system versus client) are weighed. The Rule effectively places a looming shadow over the paramount duty to protect client interests, thereby giving the tax system interests more weight.

The question now becomes whether or not the changes to Rule 1.6 will, in turn, create changes in how tax lawyers approach tax shelters and tax shelter clients. In short, the answer is no. Tax lawyers who create tax shelters will continue to use principles of confidentiality regardless of the changes because the possibility of a situation fitting within the narrow confines of Rule 1.6 is rare. This article will first outline tax shelter schemes and the problems that abusive tax shelters schemes pose to the system of taxation. Next, this article will discuss the anti-abuse rules and regulations that have developed in response to abusive tax shelters. The third section explores the depths of Model Rule 1.6 and how the Rule has been changed. Finally, the article will analyze the implications of Rule 1.6 for tax attorneys and conclude with suggestions for improvement.