Suo jure is a Latin phrase, used in English to mean 'in his own right' or 'in her own right'. In most nobility-related contexts, it means 'in her own right', since in those situations the phrase is normally used of women; in practice, especially in England, a man rarely derives any style or title from his wife (an example is Richard Neville, earl of Warwick from his wife's heritage) although this is seen in other countries when a woman is the last heir of her line. It can be used for a male when such male was initially a 'co-lord' with his father or other family member and upon the death of such family member became the sole ruler or holder of the title "in his own right" (Alone).

It is commonly encountered in the context of titles of nobility or honorary titles, e.g. Lady Mayoress, and especially in cases where a woman holds a title through her own bloodline or accomplishments rather than through her marriage.

An empress or queen who reigns suo jure is referred to as an "empress regnant" or "queen regnant", those terms often being contrasted with empress consort or queen consort: "empress" and "queen" are, however, often used alone to refer to either a regnant or consort, the distinction being indicated by context.