The law was not the "indeminity law", but the Habeas Corpus Act, and Dilorenzo misspelled "indemnity". H.R. 591 was entitled, "AN ACT To indemnify the President and other persons for suspending the privilege of the writ of habeas corpus, and acts done in pursuance thereof."
The typo "indeminity" was my typo.
Your sentence should have ended with the period inside the quotation mark.
Are you saying that the "Habeas Corpus Act" of 1863 was not enacted into law? If so, either you are mistaken, or the US Supreme Court was mistaken. In Ex parte Milligan (1866), part of the 1863 act was overturned. It seems to me that the Supreme court would not rule part of a lay unconstitutional that had not been passed in the first place.