Subject matter jurisdiction is the foundation of the law of federal courts. It is surprising and troubling that federal courts repeatedly conflate that foundational concept with the substantive merits of federal claims of right. Federal courts have been "less than meticulous" in keeping these concepts distinct. But as I previously have argued, the concepts are and must remain distinct. This is for reasons of the proper operation of the litigation process under the Federal Rules and for formalist positive-law reasons that, because Congress treats jurisdiction and substantive merits differently, courts must address and resolve them in a distinct manner.
Howard M. Wasserman,
Jurisdiction, Merits, and Substantiality
, 42 Tulsa L. Rev. 579
Available at: https://ecollections.law.fiu.edu/faculty_publications/65