Time for a legal lesson, gather round! This is interesting and it could — although, practically speaking, probably won't — be challenged in court as an over-exercise of executive power.

Part of the reason this Act isn't usually heard of is because it's pretty narrowly constructed. The President can only invoke recession/reservation (2 USC § 683) or deferral (2 USC § 684) of "budget authority" under the Act. First, this has been interpreted to mean that the President can only invoke the Act when Congress has explicitly designated that the President has discretion in budgeting under the relevant law. See, County of Santa Clara v. Trump, 250 F. Supp. 3d 497, 531 (N.D. Cal. 2017) (Noting "[w]here Congress has failed to give the President discretion in allocating funds, the President has no constitutional authority to withhold such funds and violates his obligation to faithfully execute the laws duly enacted by Congress if he does so"). Thus, every item the President redlines in the COVID bill would have to have been explicitly designated as a discretionary spending by Congress. It's not clear if this is the case, but I'm not going to read that 5,000-page mess to speculate as to what the President can and cannot rescind, so let's just assume he probably can rescind the wasteful spending he wants to.

The Act, however, provides no authority for the President to request that Congress ADD things to a piece of piece of legislation. In fact, the Congress that passed the Impoundment Act intended to prohibit the President from using the Act to effect policy changes — instead, deferments and rescissions are intended to be for routine, programmatic purposes. Consider New Haven v. United States, 809 F.2d 900, 906 (D.C. Cir. 1987):

For permanent impoundments (or "rescissions"), Congress adopted the Senate approach, which required prior legislative approval of proposed impoundments. For temporary impoundments (or "deferrals"), Congress adopted the House approach, which allowed impoundments to become effective without prior approval if neither House of Congress passed a resolution disapproving the impoundment. Importantly, Congress also amended the Anti-Deficiency Act to preclude the President from relying on that Act as authority for implementing policy impoundments.

Thus, the President's rescission of part of the COVID bill could be challenged for two reasons. First, it's unclear whether POTUS actually has the budget authority he needs to do these rescissions. Second, the recessions — both by the language and intent of the Act — cannot be based upon contingent additions to a signed law.

Practically speaking, no way in hell this gets challenged in Court. The democrats wanted greater stimulus checks, the republicans will not break with Trump. Expect the stimulus checks to be amended as requested. The only issue I predict is the Democrat-held House resisting any changes to § 230 or the initiation of voter-fraud investigations. That issue, however, is not yet before us.