What restriction applies when Congress attempts to repeal its own enactments?

The correct answer pertains to the fundamental principle that any legislation enacted by Congress is subject to the limitations imposed by the Constitution. When Congress repeals its own laws, it must ensure that the repeal does not infringe upon constitutional provisions. This is crucial because the Constitution is the supreme law of the land, and any congressional action, including the repeal of laws, must be consistent with constitutional requirements, including due process, equal protection, and other rights guaranteed.

For example, if a law protected certain rights or privileges under the Constitution, Congress cannot repeal that law in a manner that would violate those rights. This principle upholds the rule of law and ensures that legislative changes do not undermine the fundamental rights and freedoms that the Constitution guarantees to individuals.

In contrast, the other options suggest requirements that are not necessary for the repeal of legislation. For instance, while a two-thirds majority may be required for certain actions, it is not a blanket requirement for all repeals. Public notice is not a specific constitutional requirement for repeal, and Congress is not limited in its ability to repeal voluntary contracts in a manner that would suggest that such repeal is inherently more restricted than other forms of legislative repeal. Thus, understanding the supremacy of the Constitution is paramount when considering the validity of Congressional