Details at https://freerepublic.com/focus/news/4204657/posts?page=40#40.
The problem is that a bill passed by Congress cannot undue an amendment. Only another amendment can repeal a prior amendment.
It's the equivalent of a President's executive order replacing another executive order versus Congress passing a law.
In the case of the 14th amendment, the argument is whether the amnesty act only affected the participants in the Civil War or does it nullify the amendment going forward in perpetuity?
We know that no Congress can bind a future Congress. That means that Congress cannot pass a law preventing a future Congress from doing something. Only an amendment ratified by the states can do this. This means that an amnesty act cannot eliminate the insurrection clause of the 14th amendment for all future use.
-PJ