Mark V. Pauly (University of Pennsylvania, Wharton School) has published  Limiting the Tax Exclusion for Employment Based Health Insurance: Are Improved Equity and Efficiency Enough?, 62 Nat'l Tax J. 555 (2009).  Here is the abstract:

Removal or limitation of the current exclusion of employment-related health benefit payments from taxable income would improve economic efficiency and equity, but is this sufficient to make such a policy change likely? This paper uses some concepts from public choice theory, based on earlier work by Buchanan and Pauly on the incidence of tax deductibility, to suggest that such a change is more likely in the current context of broader tax reform involving a desire to reform the functioning of the health insurance market and to increase the tax share of upper middle income households.