Are tax returns protected from discovery by a qualified privilege?

Via this TaxProf blog post, I see this law student article, The Qualified Privilege Against Discovery of Federal Income Tax Returns, which references among other cases the decision by Judge Williams in Terwilliger v. York Int'l Corp., 176 F.R.D. 214 (W.D. Va. 1997), which I argued, and cite from time to time.