The non-literal scope of protection for software is intricate legally and is intricate technical. Thus, despite literally decades of court decisions and a mountain of legal scholar written on the subject in that time, it appears that there is still no consistent agreement about it, as evidenced by the Google v. Oracle which has percolated in the courts for nearly a decade and is now being heard by the US Supreme Court (oral argument was on October 7, 2020). However, the thesis of this article that a legal construct is capable of being formulated that is analytically consistent and that explains some of decisions that reach contrary outcomes (or dicta expressing some contrary views).
Hybrid IP Rights For Software, APIs, and GUIs: Understanding Copyright's Paradigm Shift,
Cath. U. J. L. & Tech
Available at: https://scholarship.law.edu/jlt/vol30/iss1/3