Definition
Compaternity is a legal and canonical concept describing the spiritual relationship — sometimes called a spiritual affinity — that arises between a godparent and a godchild (or the godchild's natural parents) through the act of sponsorship at baptism. In canon law, this relationship was treated as a form of kinship capable of producing legal consequences, most notably as an impediment to marriage between the parties so connected.
Why It Matters in Research
Compaternity is encountered primarily in two research contexts: ecclesiastical law (particularly pre-Reformation canon law and its continuing influence in Catholic jurisdictions) and historical family law, especially disputes involving the validity of marriage. Researchers working in colonial American, Latin American, or Southern European legal records will find compaternity treated as a genuine impediment; in common law jurisdictions, the concept has no surviving secular legal force and largely disappeared from Anglo-American case law.
The key trap is anachronism. A researcher encountering "compaternity" in a 17th- or 18th-century document should not assume the term is ornamental. In those contexts, a court applying canon law principles could void a marriage on compaternity grounds — treating the godparent-godchild bond as analogous to consanguinity. By the 19th century, Anglo-American civil law had fully shed this doctrine, which is why Black's both editions treat it in only a single compressed line. The absence of development in those entries signals the term's obsolescence in secular common law, not its insignificance in the records a researcher may be examining.
Researchers tracing family relationships in probate, inheritance, or legitimacy disputes arising from civil and canon law mixed jurisdictions (e.g., Louisiana, Quebec, the Philippines under Spanish rule, or ecclesiastical courts in England before the Matrimonial Causes Act 1857) should treat compaternity as a potentially operative legal concept, not mere social description.
Historical Dictionary Support
Both editions of Black's Law Dictionary give identical, minimal treatment: "Spiritual affinity, contracted by sponsorship in baptism." The compression is telling — by the time Black's was compiled, compaternity had effectively passed out of American legal relevance, and the dictionary entries function as glosses for readers encountering the term in historical materials rather than as working doctrine.
Webster's 1913 is actually more instructive here than the legal dictionaries. Its gloss — drawn from Sir John Davies — explicitly names the governing authority ("the cannon law") and the category ("spiritual affinity"), and flags the term as obsolete in ordinary usage. This alignment between the lexicographical and legal dictionaries confirms that both the legal and common usages were drawing from the same canonical source and that both were archaic by the late 19th century.
What the historical dictionaries do not address: the practical consequences of compaternity under canon law, including the degrees of affinity it created and the procedural mechanics of obtaining a dispensation. Researchers needing that level of detail must go beyond the dictionary shelf to canonical treatises or ecclesiastical court records.
Jurisdictional Note
Compaternity retains doctrinal relevance in jurisdictions governed by Catholic canon law or its derivatives. In the 1983 Code of Canon Law, spiritual relationship arising from baptism is addressed but no longer constitutes a diriment impediment to marriage — a significant doctrinal shift from earlier canonical practice. Civil law jurisdictions that historically incorporated canonical impediments (e.g., pre-modern Spanish civil law) may reflect older rules in archival and court records.