Gary Bass and Beth Kingsley have written this oped in the Washington Post:

The IRS’s improper scrutiny of conservative groups’ applications for tax-exempt status certainly warrants investigation. But we must not lose sight of the underlying problems that led to this situation: the lack of workable standards to determine what activity the Internal Revenue Service considers “political” and how much of it a nonprofit group can do….

Much of this problem could be addressed by adopting objective, substantive criteria to define political intervention for nonprofit organizations. For the past four years, we have worked with legal experts and nonprofit leaders at the Bright Lines Project (now housed at Public Citizen) to develop just such a proposal.