Looking at "Lincoln's unconstitutional and extrajudicial suspension of the Writ of Habeas Corpus. "
To be unconstitutional, unless it is just an opinion, a SCOTUS decision is needed declaring it so. No such decision exists.
Anyone can have an opinion about the Constitution, but SCOTUS decides factually..
We have Taney's ex parte Marryman but it appears to be more drama than legal. The ruling is also in the records of the district court and not the records of SCTOUS.
Ex parte Merryman - Federal Judicial Center
Prohibited Government Acts: A Reference Guide to the United States Constitution
By Jack Stark
Interesting discussion about Ex parte Merryman worth looking at but concludes.
View attachment 144453
In short war and insurrection are outside of SCOTUS review in limited circumstances.