Once Congress grants its consent to a Compact, the general view is that it may not be withdrawn. Although the matter has not been resolved by the U.S. Supreme Court, two federal circuit courts of appeal have held that congressional consent, once given, is likely not subject to alteration. Tobin v. United States, 306 F.2d 270, 273 (D.C. Cir. 1962) (“such a holding would stir up an air of uncertainty in those areas of our national life presently affected by the existence of these Compacts. No doubt the suspicion of even potential impermanency would be damaging to the very concept of interstate Compacts.”); Mineo v. Port Auth. of N.Y. & N.J., 779 F.2d 939 (3d Cir. 1985) (following Tobin).

Notwithstanding Tobin and Mineo, Congress specifically reserves the right to alter, amend, or repeal its consent as a condition of approval in several Compacts. See, e.g., Congress’ consent to the Tahoe Regional Planning Compact, Pub. L. No. 96-551 § 7, 94 Stat. 3233, 3253 (1980). Embodiment of the reservation of congressional authority exists in Congress’ consent to low-level radioactive waste disposal Compacts states that reads, “Each Compact shall provide that every 5 years after the Compact has taken effect that Congress may by law withdraw its consent.” 42 U.S.C. § 2021d(d). Express reservations provide prior notice to the states, but no court decision has addressed whether these reservations are proper or raise the concerns expressed in Tobin and Mineo.

Notwithstanding the courts’ concerns in Tobin and Mineo, Congress may legislate within the subject matter of a Compact to which it has granted previous consent, which could have the effect of changing the landscape in which a Compact operates or making a Compact obsolete. BUENGER, ET AL., supra, at 89; Arizona v. California, 373 U.S. 546, 565 (1963) (Congress is within its authority to create a comprehensive scheme for managing the Colorado River, notwithstanding its consent to the Colorado River Compact). There is one exception to this general rule regarding Congress’ retained authority. Article IV of the U.S. Constitution guarantees the territorial integrity of the states; thus, once Congress consents to a state boundary Compact, it may not subsequently adopt legislation undoing the states’ agreement.

If Congress modifies a condition of its consent, the states would need to enact that modification into their Compact. BUENGER, ET AL., supra, at 89. There is no case law on this issue, but a Compact requiring consent cannot be valid if it conflicts with Congress’ conditions of consent.