Abeyance
Abeyance (from the Old French abeance meaning "gaping") is a state of expectancy in respect of property, titles or office, when the right to them is not vested in any one person, but awaits the appearance or determination of the true owner. In law, the term abeyance can be applied only to such future estates as have not yet vested or possibly may not vest. For example, an estate is granted to A for life, with remainder to the heir of B. Following A's death, if B is still alive, the remainder is in abeyance, for B has no heirs until B's death. Similarly, the freehold of a benefice, on the death of the incumbent, is said to be in abeyance until the next incumbent takes possession.
It is common, but incorrect, to speak of peerage dignities which are dormant (i.e. unclaimed) as being in abeyance.
History in the United Kingdom
The most common use of the term is in the case of English peerage dignities. Most English peerages pass to heirs-male, but the ancient baronies created by writ, as well as some very old earldoms, pass instead to heirs-general (by cognatic primogeniture). In this system, sons are preferred from eldest to youngest, the heirs of a son over the next son, and any son over daughters, but there is no preference among daughters: they or their heirs inherit equally.
If the daughter is an only child or her sisters are deceased and have no living issue, she (or her heir) is vested with the title; otherwise, since a peerage cannot be shared nor divided, the dignity goes into abeyance between the sisters or their heirs, and is held by no one. If through lack of issue, marriage, or both, eventually only one person represents the claims of all the sisters, they can claim the dignity as a matter of right, and the abeyance is said to be terminated. On the other hand, the number of prospective heirs can grow quite large, since each share potentially can be divided between daughters, where the owner of a share dies without leaving a son.
A co-heir may petition the Crown for a termination of the abeyance. The Crown may choose to grant the petition, but if there is any doubt whatsoever as to the pedigree of the petitioner, the claim is normally referred to the Committee for Privileges. If the claim is unopposed, the committee will generally award the claim, unless there is evidence of collusion, the peerage has been in abeyance for more than a century, or the petitioner holds less than one-third of the claim.
This doctrine is a 17th-century innovation, although it is now applied retrospectively for centuries. It cannot be applied perfectly; for example, the eighth Baron De La Warr had three surviving sons; the first died without children, the second left two daughters, and the third left a son. In modern law, the title would have fallen into abeyance between the two daughters of the second son, and nobody else would have been able to claim it even if the abeyance were settled; however, in 1597, the grandson of the third son (whose father had been re-created Baron De La Warr in 1570) claimed the title and its precedence.
It is possible for a peerage to remain in abeyance for centuries. For example, the Barony of Grey of Codnor was in abeyance for over 490 years between 1496 and 1989, and the Barony of Hastings was similarly in abeyance for over 299 years from 1542 to 1841. Some other baronies became abeyant in the 13th century, and the abeyance has yet to be terminated. The only modern examples of titles other than a barony that have yet gone into abeyance are the earldom of Arlington and the viscountcy of Thetford, which are united, and (as noted above) the earldom of Cromartie.
In Westarctica
As the Peerage of Westarctica is far less formalized than the British system, it is easier for a title to go into abeyance. Upon the death of a peer, every effort is made to ensure their rightful heir becomes the new recipient of their rightful title. However, in every current case of a Westarctican peer passing away, their rightful heirs were not easily reachable or were difficult to determine. In these cases, the titles are currently held in abeyance pending a rightful heir reaching out to the Government of Westarctica to request ownership of their title.