Since each realm has the same person as its monarch, the diplomatic practice of exchanging ambassadors with letters of credence and recall from one head of state to another is redundant.
In recent years, advocates have argued for free movement of citizens among a subset of the Commonwealth realms: the United Kingdom, Canada, Australia, and New Zealand, which they argue "share the same head of state, the same native language, [and] the same respect for the common law."[REF][REF][REF][REF]