Definition
Mulier puisne (also spelled mulier puisné) is a common law term of law French describing the younger legitimate son born of a marriage, in a specific family circumstance: the father had previously fathered a bastard son by the mother before their marriage, and after the marriage a legitimate son was born. That younger, legitimate son is the mulier puisne. He stands in contrast to the elder illegitimate son — the bastard eigné — who was born before the marriage and therefore could not be legitimated under English common law regardless of the subsequent marriage.
The term operates as one half of a paired legal distinction. Neither term has meaning without the other. Mulier puisne means, essentially, the younger legitimate heir, and bastard eigné means the elder illegitimate one. The legal consequence of the distinction was significant in the law of inheritance and seisin: in certain circumstances, if the bastard eigné entered and held land unchallenged, his possession could be protected even against the mulier puisne's technically superior title.
Common Confusion
Mulier puisne is easily confused with bastard eigné, and the two terms must be understood together. The confusion runs deeper than terminology. A researcher encountering historical disputes over land inheritance may find that the bastard eigné — the elder, illegitimate son — held seisin of the land and was protected against the mulier puisne's claim, despite the mulier puisne's legitimate birth giving him the stronger technical title. This apparent inversion (the illegitimate son prevailing over the legitimate one) arises from the common law's heavy weight on uncontested seisin and the equitable reluctance to disturb long-held possession. The legitimacy of the mulier puisne did not automatically translate into a winning claim if the bastard eigné had possessed the land peaceably during the father's lifetime and the father died without disturbing that possession.
Why It Matters in Research
This term surfaces almost exclusively in medieval and early modern English common law materials, particularly in the law of real property, descent, and inheritance. Researchers working in English land law history, Year Books, Bracton, Littleton, or Coke on Littleton will encounter this pairing in discussions of seisin, descent cast, and the protection of possession.
The critical research trap is reading mulier puisne in isolation. The term means almost nothing without its counterpart, bastard eigné. Any source that defines one without the other — as Anderson's and Bouvier's effectively do by cross-referencing only — is directing the researcher to do necessary follow-up work. Black's gives the operative family scenario, but the full legal consequence (when the bastard eigné's seisin could defeat the mulier puisne's claim) requires consulting treatise-level sources such as Littleton's Tenures or Coke's commentary on it.
This term is effectively extinct in modern practice. No American jurisdiction applies this doctrine. It appears in contemporary research only when:
(1) tracing the historical development of legitimacy doctrines in Anglo-American law;
(2) researching the history of seisin and its consequences for title;
(3) reading primary common law sources that presuppose familiarity with law French terminology.
Researchers should also note that the broader question of whether subsequent marriage legitimated a previously born illegitimate child was answered differently in canon law (yes) and English common law (no) — a divergence that created the very problem mulier puisne addresses, and that generated significant conflict between ecclesiastical and common law courts in medieval England.
Historical Dictionary Support
The three shelf sources handle this term with varying degrees of usefulness. Black's provides the only substantive definition, setting out the precise family scenario that generates the two characters — the bastard cigné (Black's spelling of eigné) and the mulier puisné — in a single compact sentence. It is accurate as far as it goes but does not address the legal consequences of the distinction in land law.
Anderson's and Bouvier's both simply redirect to related entries (EIGN and BASTARD EIGNE, respectively), which is honest but unhelpful as a starting point. A researcher who arrives at mulier puisne first will be sent back and forth between entries without landing on a full explanation in any one of them. This cross-reference structure reflects how law French paired terms were treated in 19th-century legal dictionaries — as a cluster to be understood together rather than separately defined — but it serves modern researchers poorly.
None of the three shelf sources explains the seisin-based exception that could allow the bastard eigné to prevail over the mulier puisne, which is arguably the most legally significant aspect of the distinction. For that analysis, treatise sources are essential.
Jurisdictional Note
This doctrine is specific to English common law and has no operative application in any American jurisdiction. It may appear in colonial-era American property disputes litigated under inherited English common law rules, but it is not a living doctrine. Research use is historical only.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Bastard Eigné and Mulier Puisne; Legitimacy in English Common Law; Seisin and Descent Cast.