Definition
A Latin legal term meaning "having the same power" or "of equal authority." In its legal usage, *tatis* functions as a shorthand descriptor applied to a person who holds coordinate authority with another — that is, one who shares equivalent power, standing, or office. The concept appears primarily in the context of co-officials, joint officers, or others who exercise concurrent and coequal jurisdiction or authority. Bouvier traces the term with the cross-reference to *collega*, indicating its use in describing a colleague or co-officer in the classical Roman sense of shared magistracy or joint commission.
Common Language
Modern common usage (Wiktionary): Plural of *tati* — no legal significance in this form.
The common-language form is simply a grammatical plural with no legal content. The legal term *tatis* is an entirely distinct Latin genitive or adjectival form, unrelated to the Wiktionary entry. Researchers should not be confused by the surface similarity; the legal usage has no connection to the modern common-language form.
Common Confusion
*Tatis* should not be confused with *totidem* (just so many; the same number) or *totis viribus* (with all one's powers), which are distinct Latin phrases occasionally encountered in similar archaic legal contexts. The specific meaning of co-equal authority in *tatis* is more precisely tracked through *collega* and the concept of coordinate jurisdiction.
Why It Matters in Research
*Tatis* is a term researchers are unlikely to encounter as a standalone headword in modern legal materials. It surfaces almost exclusively in older common law and civil law commentary, and in digests that carry forward Latin maxims and abbreviations from Roman or canon law sources. Its appearance in Bouvier paired with a cross-reference to *qui tam* and *collega* suggests it was used in the context of joint authority and shared enforcement standing — a conceptual neighborhood that matters significantly in historical research on multi-officer courts, joint commissions, and statutory penalty actions.
Researchers working in pre-twentieth-century American or English materials should be alert to the term appearing parenthetically or in passing rather than as a defined term of art. It is more likely to appear in footnotes, Latin glossaries, or digests than in operative legal text. The Rapalje & Lawrence entry is unhelpfully circular, redirecting to *trespass* without meaningful explanation — a reminder that historical dictionary cross-referencing can obscure as much as it illuminates.
The conceptual content — co-equal authority between officers — connects meaningfully to research on *qui tam* actions, where a private relator sues alongside or in the name of the government. The shared-authority dimension of *tatis* maps onto the dual standing structure of *qui tam* enforcement, where both the relator and the sovereign hold concurrent interest in the penalty. Researchers tracing the historical roots of *qui tam* standing may encounter *tatis* in that theoretical apparatus.
Historical Dictionary Support
Bouvier's entry is the more substantive of the two sources, defining *tatis* as "one having the same power with another" and directing readers to *collega* — the Roman concept of a colleague sharing equal official power. This reflects the civil law background of the term, where co-magistrates in Roman public law (consuls, censors, tribunes) exercised coordinate and mutually checking authority. The pairing with *qui tam* in Bouvier's layout appears to be an artifact of alphabetical proximity rather than conceptual identity, though the relational-authority dimension of both terms is not entirely without connection.
Rapalje & Lawrence provides no independent treatment, redirecting to *trespass* entries in a manner that does not illuminate *tatis* at all. This divergence between the two sources is itself informative: it suggests *tatis* was not a term with stable, widely recognized usage in American common law practice, but rather a civil-law borrowing that some compilers included for completeness while others effectively ignored.
Neither source provides case law citations in connection with the term. Modern legal dictionaries, including Black's, do not carry *tatis* as a headword, confirming its obsolescence as an operative term.