The use of Century Schoolbook by the Supreme Court is more a matter of their accepting the default selection of the Government Printing Office (GPO) --- before they switched to using Adobe InDesign, their updated design manual was available as a PDF typeset by "ACOMP.exe" (anyone know anything about it? Apparently it was a custom typesetting tool which made PDFs from XML?) which was visually indistinguishable from an earlier edition style guide I had printed during WWII (with a note about paper shortages in it).

See:

https://www.govinfo.gov/collection/gpo-style-manual

and contrast 2000 to 1984 and earlier.