Peerage Disputes
The Crown, as fount of honour, may determine all petitions claiming peerages. The Sovereign upon the Attorney-General's advice can grant the claim or, in contentious matters, send it to the House of Lords, who in turn send it to the Select Committee for Privileges. (The House of Lords appoints 16 peers – including the Chairman of Committees – to the Committee.) Next, the sovereign makes a final decision based upon the Committee for Privileges' recommendation.
The Committee for Privileges also has a rôle in terminating abeyant peerages. A co-heir may petition the sovereign for a termination of the abeyance in his or her favour; the sovereign can choose to grant the petition, but if there is any doubt as to the petitioner's pedigree, the claim is usually referred to the Committee for Privileges. If the claim is unopposed, the Committee will generally award the claim to the petitioner. Under a decision of 1927, however, the Committee can deny a claim if the peerage has been in abeyance for more than 100 years, or if the petitioner holds less than 1/3 of the claim (an eldest son would inherit all of his parent's claim, while daughters divide their parent's claim amongst them in the absence of sons). Incidentally, the House of Lords made a standing order in 1954 directing that the Committee may deny a claim if the co-heirs have entered into an "improper arrangement." This rule prevents co-heirs of multiple baronies by writ from agreeing not to contest each other's claims, thereby dividing the baronies by writ amongst themselves.
In claims regarding the Peerage of Scotland, the Court of the Lord Lyon King of Arms in Scotland determines the rightful heir or heiress to an aristocratic title. These titles (as in England) are composed of Dukedoms, Marquessates, Earldoms, and Viscounties, plus Lordships (which are the equivalent of Baronies in the Peerage of England). Theoretically, only the Lords have jurisdiction over succession to peerages, but the Lyon Court does have jurisdiction over succession to coats-of-arms. Under Scottish law, an individual's heir succeeds to his arms undifferenced, while other descendants may succeed to arms differenced by special marks, called cadency marks. The case before the Lyon Court involves a dispute as to who may lawfully succeed to a deceased peer's (i.e., aristocrat's) arms "undifferenced" — the lawful successor to the arms will normally also be the successor to the peerage.
For further information about the Committee for Privileges, see: http://www.publications.parliament.uk/pa/ld/ldprivi.htm
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