Article. It's short and readable, yet provides an insight into the way that ethics for tax lawyers is different than for most of us. (For those of you who teach PR but aren't tax lawyers, Hatfield's "The Ethics of Tax Law: An Introduction" is probably the most useful single article you can read.) Here's the abstract for The Tax Sections Ethics Debate:
The recent American Bar Association Section of Taxation debate on standards of advice and disclosure is not new among tax lawyers. The legal ethics literature reports tax lawyers discussing these issues in the 1950s and 1960s. Having neither the benefit of formal ethics opinions or committee work, for good or not, the debate was more open-ended, oriented more around the ethics of lawyering than the law of lawyering.