New disclosure rules proposed by Treasury and IRS

"Dark money" groups, ranging from the National Rifle Association on the right to the American Civil Liberties Union on the left, won't have to provide the names and addresses of major donors if rules recently proposed by the Treasury Department and IRS are accepted.

While groups will still be required to report the amounts of substantial donations and keep detailed records on hand, donor files would only be reviewed by the IRS on a case-by-case basis, according to The Hill.

The IRS tried to lower the donor disclosure requirements for 501(c)(4) nonprofits last year, but the procedure was set aside by a Montana judge who said there hadn't been a proper notice and comment period.