A rubro ad nigrum
Defined in 2 dictionaries — Ballentine's (1916), Black's (1910)
Ballentine's Law Dictionary
James A. Ballentine · 1916
From the red title of a statute to the black body thereof.
Black's Law Dictionary
Henry Campbell Black, M.A. · 1910
Lat. From the red to the black; from the rubric or title of a statute, (which, anciently, was in red letters,) to its body, which was in the ordinary black. Tray. Lat Max.; Bell, "Rubric."