Suppose that some action has been committed that is virtually universally seen as heinously immoral and worthy of punishment. However, there is technically no law against the action at the time, and ex post facto laws are unconstitutional, so nothing can be done by normal legislative and/or judicial procedures.
If there is sufficiently widespread support for punishing the offender, could an amendment to the Constitution be passed authorizing an ex post facto law for this purpose?
Yes, a constitutional amendment could simply say something like, "notwithstanding the prohibition on ex post facto laws, congress may enact..."
The Constitution can never violate itself. And the Constitution does not constrain the content of future amendments to itself other than the guarantee of "equal suffrage in the Senate."
Sections that appear to be contradictory would be construed to be harmonious.
A subsequent amendment that expressly allows what a pre-existing section would otherwise prohibit would be harmonious, especially if written to be operative "notwithstanding" the purported conflicting section.
