I read an interesting article on this not too long ago.  It was dated 5/29/19 on TheTaxBook website but it's protected so that only TTB customers can access it.

It references a TC case though (unfortunately not exactly "plain language")

Feigh, 152 TC No. 15, May 15, 2019

https://www.ustaxcourt.gov/UstcInOp/OpinionViewer.aspx?ID=11863

The EITC and the ACTC are acts of legislative grace provided by Congress. We know the familiar rule that deductions and credits "depend upon legislative grace and are allowed only to the extent authorized by statute."  Our holding addresses the power of the IRS, through a notice, to deem income otherwise includible as not includible for purposes of calculating a benefit bestowed by Congress. We do not reach the related issue of whether the IRS may properly classify income as not includible through a regulation.  However, the IRS is not free to circumscribe the credits that the legislature has chosen to authorize through statute; that is a power only Congress has. Therefore, to the extent [the IRS] seeks to use Notice 2014-7, supra, to deprive petitioners of a benefit bestowed by Congress, we hold [the IRS] may not do so.