Decisory oath
{{Short description|Oath that conclusively resolves a factual dispute}}
A decisory oath or decisive oath{{cite book | title = Black's Law Dictionary | edition = 8th | page = 1101 | isbn = 0314151990 }} is a oath that can decide a fact at issue in a legal dispute.{{Cite book | url = https://books.google.com/books?id=6OJf9CbgKTkC&pg=PA119 | page = 119 | title = The Civil Law Tradition: An Introduction to the Legal Systems of Europe and Latin America | edition = 3rd | author1-first = John Henry | author1-last = Merryman | author2-first = Rogelio | author2-last = Pérez-Perdomo | publisher = Stanford University Press | year = 2007 | isbn = 9780804755696}} A decisory oath that disclaims fault is also called an exculpatory oath.
Limited forms of decisory oath are found in some present-day civil law legal systems, where they are limited to civil litigation, and in some customary law systems. Historically decisory oaths enjoyed wide use, including in legal systems of Babylon and ancient Greece.
In civil law
Decisory oaths are specifically provided for in the civil codes of certain civil law systems, including France,{{Cite web | url = https://www.dalloz.fr/documentation/Document?id=CCIV174765&FromId=CODES_SECS_CCIV | work = Code civil | language = fr | title = SOUS-SECTION 1 Le serment décisoire | access-date = 2024-10-30}} Italy,{{Cite web | url = http://studiolegalesola.com/effetti-del-giuramento-decisorio-nel-giudizio-civile/ | publisher = Studio Legale Sola | title = Effetti del giuramento decisorio | access-date = 2024-10-30 | language = it}}{{Cite web | url = https://www.treccani.it/enciclopedia/giuramento-diritto-processuale-civile/ | title = Giuramento | language = it | access-date = 2024-10-30 | work = Enciclopedia Italiana Treccani}} and Puerto Rico.{{Cite web | url = https://law.justia.com/codes/puerto-rico/title-thirty-one/subtitle-4/part-i/chapter-249/subchapter-ii/3298/ | title = § 3298 - Weight of confession under decisory oath | access-date = 2024-10-30 | work = 2023 Laws of Puerto Rico }} However, its modern use in these systems is largely tactical.{{sfn|Merryman|Pérez-Perdomo|2007|p=120}} In these systems, when decisory oaths are allowed, they must be requested (or "referred") by the opposing party; having requested the oath, the requesting party is bound by it and is not permitted to present any proof that it is false.
If instead the second party requests that the first party demand the oath from it ("deferring" the oath), the first party does so, and the second party then refuses to swear, it is the second party that loses the case.{{Cite web | work = Juridictionnaire | language =fr | publisher = Government of Canada | access-date = 2024-10-30 | url = https://www.noslangues-ourlanguages.gc.ca/fr/juridictionnaire/decisoire-suppletoire | title = décisoire / supplétoire }}
According to John Henry Merryman, "The Decisory Oath worked in the following way: Party A could put Party B on his oath as to a fact at issue that was within Party B's knowledge. If Party B refused to swear, the fact was taken as conclusively proved against him. If Party B swore, the fact was taken as conclusively proved in his favor."John Henry Merryman, The Civil Law Tradition (Stanford: Stanford University Press, 1969): 126, as cited in Immanuel Kant, The Metaphysics of Morals, ed. Mary Gregor (Cambridge: Cambridge University Press, 1996): 83n25 (emphasis added) Mary Gregor explains that this procedure was "designed to protect the judge from threats from the wealthy and the powerful."Kant, loc. cit.
Decisory oaths were abolished in Brazilian law in 1850 by the commercial litigation reform of Regulamento 737; prior to that, a creditor seeking to avoid prescription of a debt could defeat the presumption that the debt had been paid by demanding a decisory oath from the debtor.{{Cite book | author = Luiz Frederico Sauerbronn Carpenter | title = Manual do Código civil brasileiro | volume = 4 | publisher = J. Ribeiro dos Santos | year = 1919 | url = https://books.google.com/books?id=y6nGguqTquAC&pg=PA435 | page = 435 | language = pt}}
In other legal traditions
Decisory oaths play a significant role in many African systems of customary law, including those of Niger.{{Cite journal | url = https://scholarship.law.unc.edu/cgi/viewcontent.cgi?article=2131&context=ncilj | format = pdf | author-first = Thomas A. III | author-last = Kelley | title = Truth or Consequences (the Deadly Kind): Oath Swearing in Nigerien Customary Law | volume = 47 | journal = North Carolina Journal of International Law | issue = 3 | page = 331, 349 | year = 2022 }} In the customary law of Nigeria, a person may swear a juju oath calling for themselves to be struck dead within the year if they are speaking falsely.{{sfn|Kelley|2022|p=351-352}}
Decisory oaths are also found in the Babylonian Code of Hammurabi{{Cite journal | url = https://kb.osu.edu/server/api/core/bitstreams/4fade0d4-95b2-5bb4-ae81-a0c2cc14e874/content | format = pdf | author-last = Milhizer | author-first = Eugene R. | title = So help me Allah: An historical and prudential analysis of oaths as applied to the current controversy of the Bible and Quran in oath practices in America | journal = Ohio State Law Journal | volume = 70 | year = 2009 | page = 1, 9 n.29}} and are also mentioned in the Old Testament in chapter 22 of the Book of Exodus, which provides that someone who receives an animal for safekeeping that then dies can avoid any liability by swearing a decisory oath.{{sfn|Milhizer|2009|p= 8 n.27}} They are also found in Talmudic law.{{Cite journal | journal = American Law Register | author-first = Thomas Raeburn | author-last = White | year = 1903 | url = https://scholarship.law.upenn.edu/cgi/viewcontent.cgi?article=6402&context=penn_law_review | format = pdf | title = Oaths In Judicial Proceedings And Their Effect Upon The Competency of Witnesses | page = 384 n.16}} Decisory oaths may also have served as a means of resolving criminal prosecutions in ancient Greek law. There is no historical record of a prosecution being ended in this way, but decisory oaths are mentioned in the Gortyn code.{{Cite journal | url = https://www.researchgate.net/profile/Robert-Leib/publication/337883520_I_Nomi_Degli_Dei_A_Reconsideration_of_Agamben's_Oath_Complex/links/5f551870299bf13a31a71a62/I-Nomi-Degli-Dei-A-Reconsideration-of-Agambens-Oath-Complex.pdf | title = I Nomi Degli Dei: A Reconsideration of Agamben’s Oath Complex | author-last = Leib | author-first = R.S. | journal = Law Critique | volume = 31 | page = 89 n.35 | year = 2020 | doi = 10.1007/s10978-019-09253-8}}