In the context of the English peerage, a woman is described as a peeress 'suo jure' when she possesses a dignity by virtue of her own descent or a unique royal grant, as opposed to a peerage by courtesy acquired through marriage to a titled husband. Historically, while women were largely excluded from legislative participation in the House of Lords until the Life Peerages Act 1958, certain baronies created by writ—and a limited number of earldoms—allowed for female succession in the absence of male heirs (known as falling into abeyance or passing to the eldest daughter depending on the specific remainders).
From a heraldic perspective, a 'suo jure' peeress enjoys the right to bear her paternal arms upon a lozenge, topped with the coronet of her rank. If she is married, she may impale her arms with those of her husband, but her title remains distinct and does not confer the peerage rank upon her spouse. Such titles are fundamental to the study of feudal land tenure and the evolution of the primogeniture system, representing rare instances where female agency was codified within the rigid hierarchies of the English class system.