Definition
A modus de non decimando is a claimed customary right or prescriptive exemption from paying tithes entirely. The doctrine arises in English ecclesiastical law and refers to an asserted local custom under which a landholder claims to owe no tithes at all — not a reduced payment, not a substituted payment, but a complete exemption from the tithe obligation.
The rule is that such a prescription is void. English law did not recognize a general customary right to be entirely free of tithes, on the theory that no valid custom could exist by which the Church was stripped of its established entitlement altogether. The sole recognized exception was abbey lands — property formerly belonging to dissolved monasteries — where a historical exemption predating the Reformation could survive as a genuine prescriptive claim.
The maxim encapsulating the rule: Modus de non decimando non valet. A prescription not to pay tithes is not valid.
Common Confusion
The term modus de non decimando is easily confused with modus decimandi, which is a related but distinct concept. A modus decimandi is a valid local custom by which tithes are paid in a particular manner or in a substituted form — a fixed money payment, a portion of produce calculated differently, or some other agreed equivalent. The key distinction is that a modus decimandi modifies the form of payment; a modus de non decimando attempts to eliminate the obligation entirely. English law tolerated the former and rejected the latter. A researcher encountering a tithe dispute must identify which type of claim is at issue, because the legal treatment is opposite: one is presumptively valid if sufficiently established, the other is presumptively void.
Why It Matters in Research
This term appears almost exclusively in pre-twentieth-century English ecclesiastical and property law sources. Researchers encountering it will typically be working in one of three contexts: tithe litigation records, ecclesiastical court proceedings, or commentary on the effects of the Dissolution of the Monasteries on landholding.
The abbey lands exception is the most practically significant angle for historical research. When monastic property passed into private hands following the Henrician dissolution, questions arose as to whether tithe exemptions that had attached to those lands as ecclesiastical property survived the transfer. Courts recognized that abbey lands retained their exemption — not as a new prescriptive claim but as a continuation of an existing one — giving this doctrine real stakes in post-Reformation property disputes.
Researchers using older digests and abridgments should be aware that tithe law occupies an unusually specialized corner of English legal history. The doctrines of modus decimandi, modus de non decimando, and various statutory modifications to tithe obligations were heavily litigated through the ecclesiastical courts and later the equity courts. The Tithe Commutation Act 1836 rendered most of these distinctions moot for practical purposes by converting tithe obligations to rent-charges, so corpus materials from after that date will rarely engage with this term directly. Materials from the sixteenth through early nineteenth centuries are where this doctrine appears in live controversy.
Cross-reference to related ecclesiastical and property terms is essential: tithe disputes frequently involved questions of prescription, custom, and the distinction between lay and ecclesiastical jurisdiction, all of which have their own doctrinal histories.
Historical Dictionary Support
Black's Law Dictionary and Bouvier's Law Dictionary are in complete agreement on this term, which is unsurprising given that Bouvier draws heavily on Blackstone for ecclesiastical law topics and Black's follows the same lineage. Both cite Sharswood's edition of Blackstone's Commentaries as the primary authority. Black's adds citations to Lofft 427 and Croke's Elizabethan reports, grounding the rule in case law from the period when tithe litigation was most active.
Neither dictionary elaborates on the abbey lands exception beyond noting it, and neither explains the doctrinal rationale in depth — namely, that English courts treated a complete exemption from tithes as fundamentally inconsistent with the nature of custom, since custom must be reasonable, and it was considered unreasonable for any custom to deprive the Church entirely of a legally established revenue. Researchers wanting the full theoretical underpinning will need to consult Blackstone's Commentaries directly (Book II, Chapter 3 on tithes) and the tithe-specific treatises of the period. The historical dictionaries serve as reliable pointers but not as complete explanations.
Jurisdictional Note
This doctrine is exclusively English in origin and has no meaningful American legal counterpart. The United States never adopted a tithe system as a legal obligation, and the First Amendment's Establishment Clause foreclosed any parallel development. Researchers in American legal sources will not encounter this term in live litigation; it appears only in historical or comparative contexts.