Canonum De Ius Rex
Canons of Sovereign Law
II. Sovereign
2.1 Sovereign Claim
Article 23 - Royal Blood Right
Canon 5537 (link)
As the literal and true meaning of “Royal” is to be the progeny of a King or Queen, the term has been further qualified to mean progeny of the “Royal Family” and “Imperial Family”, thereby enabling the exclusion of certain offspring who may be politically deemed “illegitimate” by birth, even though they carry Royal Blood.
Canon 5538 (link)
In most societies that retain monarchies, possessing “Royal Blood” as a claimed Right does not in itself bestow an automatic birthright to be Sovereign, because of successive historic laws that require a suitable candidate to not only possess “Royal Blood” but be regarded as a legitimate and approved member of the “Royal Family”.