Definition
Cohabitation is the act of living together in the same dwelling, typically used in law to describe two persons sharing a common household with the characteristics of a domestic partnership. The term carries distinct meanings depending on context:
(1) Marital cohabitation: The living together of spouses as husband and wife, fulfilling the mutual domestic obligations of marriage. Historically, cohabitation was both a right and a duty of marriage — a spouse could be compelled to resume it, and wrongful refusal could constitute grounds for divorce or separation.
(2) Unlawful or illicit cohabitation: The living together of an unmarried man and woman in a sexual relationship. Under older statutes, this was a criminal offense in many jurisdictions, particularly where the relationship was openly adulterous or involved a man living with multiple women in a polygamous arrangement.
(3) Modern unmarried cohabitation: Two persons, not legally married, sharing a common residence in an intimate domestic relationship. This is the predominant legal usage today, triggering questions of property rights, support obligations, parental rights, and the enforceability of cohabitation agreements.
In all contexts, cohabitation requires more than occasional visits or temporary stays — there must be a shared habitation with some degree of permanence and domestic character. Sexual intercourse is not strictly required for the definition, though it is often presumed or relevant.
Common Language
Modern common usage (Wiktionary): An emotional and physical intimate relationship including a common living place, existing without legal or religious sanction; also, simply the act of living together.
Historical common usage (Webster's 1913): The act or state of dwelling together, or in the same place with another; the living together of a man and woman in supposed sexual relationship.
The common-language definitions treat cohabitation primarily as a factual living arrangement, with or without legal significance. The legal definitions carry heavier weight: cohabitation can trigger statutory consequences, affect marital rights and duties, alter property claims between partners, modify spousal support obligations upon remarriage or post-divorce cohabitation, and in historical law could constitute a criminal offense. A term that sounds purely descriptive in ordinary usage is, in law, a threshold concept with significant procedural and substantive consequences.
Common Confusion
COHABITATION CLAUSES IN DIVORCE INSTRUMENTS
Modern divorce decrees and separation agreements frequently include cohabitation clauses that terminate or reduce alimony if the recipient spouse begins cohabiting with another person. The legal definition of cohabitation for this purpose is often defined by statute or case law and may differ from the general definition — some jurisdictions require a romantic or sexual relationship, others require shared finances, and still others apply a strict domicile test. Researchers should not assume a uniform standard when working across jurisdictions or time periods.
Why It Matters in Research
Cohabitation is a term whose legal significance has shifted dramatically across time, making careful attention to period and jurisdiction essential.
In historical sources through the late nineteenth and early twentieth centuries, the dominant legal concern was unlawful cohabitation — criminal statutes targeting adultery, fornication, and polygamous arrangements. Cases in this era often turn on whether the parties' living arrangement was sufficiently open, notorious, or continuous to satisfy the statutory elements. The Pennsylvania case cited in both editions of Black's (75 Pa. 211) and the Alabama and Arkansas cases in the second edition reflect this criminal enforcement context. Researchers should not read modern cohabitation doctrine backward into these sources.
The mid-twentieth century saw cohabitation's legal significance shift to divorce law, particularly the effect of a recipient spouse's post-divorce cohabitation on alimony obligations. Many states enacted or amended statutes during this period, and the case law is heavily jurisdiction-specific.
Contemporary doctrine centers on the rights and obligations of unmarried cohabitants inter se — property division, palimony claims, contract enforcement, and parentage. The Law Mind Encyclopedia entries on unmarried cohabitants address these modern frameworks directly.
A persistent trap in historical research is the overlap between cohabitation and meretricious relationship. The historical sources use "meretricious intercourse" to mean illicit or unlawful sexual cohabitation — not the modern "meretricious relationship" doctrine developed by courts in Washington and other states to allocate property between unmarried partners. The same word signals different legal frameworks depending on the era.
Bouvier's important qualification — that cohabitation does not necessarily imply sexual intercourse — is worth noting for researchers dealing with definitions in factual or evidentiary disputes, particularly in the context of same-sex partners, caregiving relationships, or cohabitation clauses in support agreements.
Historical Dictionary Support
The historical dictionaries agree on the core physical element: cohabitation requires shared habitation with some permanence, not mere visits or temporary stays. Both editions of Black's carry identical language on this threshold, warning against confusing cohabitation with "a sojourn, a habit of visiting or remaining for a time." This language traces to In re Yardley's Estate, 75 Pa. 211, cited in the second edition.
Bouvier's is the most nuanced of the historical sources on the sexual element, explicitly stating that cohabitation "does not necessarily imply sexual intercourse" and that it "may be used with reference to married or unmarried persons." This is broader than popular usage and somewhat broader than the Black's framing, which contextualizes cohabitation primarily as living together "as husband and wife."
Rapalje & Lawrence contribute the most practically useful historical point: contracts made in consideration of future illicit cohabitation are void as against public policy, but contracts made in consideration of past cohabitation were treated as valid (being in consideration of nothing, the past cohabitation being already performed). This distinction had real significance in historical enforcement of financial arrangements between unmarried partners and is a precursor to the modern palimony debate.
None of the historical dictionaries address cohabitation clauses in modern divorce instruments or the rights of unmarried cohabitants as a positive legal framework — these are entirely twentieth and twenty-first century developments not captured in these sources.
Jurisdictional Note
Cohabitation's legal consequences vary substantially across American jurisdictions. Roughly half of U.S. states have statutes that terminate or modify alimony upon the recipient's cohabitation, but the definitions and thresholds differ widely. Common-law marriage, which cohabitation can help establish, is recognized in only a minority of states. Criminal statutes targeting cohabitation, once widespread, have been largely repealed or rendered unenforceable following Lawrence v. Texas, 539 U.S. 558 (2003).
Encyclopedia Cross-Reference
Unmarried Cohabitants — Property Rights and Division (The Law Mind Family Law Encyclopedia)
Unmarried Cohabitants — Palimony and Support Obligations (The Law Mind Family Law Encyclopedia)
Unmarried Cohabitants — Parentage Rights of Unmarried Partners (The Law Mind Family Law Encyclopedia)