Whole law presumes the ORIGINAL ACT OF CONGRESS is in question, lawyers call it a facial challenge. On its face means “as written”.
That requires & limits the inspection by the court to that and only that (words from the beginning) of the coded law. Facial ex post challenges require the defense to attack the root of the regime and not the middle ( amendments). It also permits congressional material like committee minutes, floor speeches, etc.
The failed because they attacked the middle. A common error among pro se suits.
Hope this helps.