from
Bouvier's Law Dictionary, Revised 6th Ed (1856)
ROYAL HONORS. In diplomatic language by this term is understood the rights
enjoyed by every empire or kingdom in Europe, by the pope, the grand duchies
of Germany, and the Germanic, and Swiss confederations, to precedence over
all others who do not enjoy the same rank, with the exclusive right of
sending to other states public ministers of the first rank, as ambassadors,
together with other distinctive titles and ceremonies. Vattel, Law of Nat.
B. 2, c. 3, Sec. 38; Wheat. Intern. Law, pt. 2, c. 3, Sec. 2.