arxo

Rifat Jumagulov · How this is checked

The Same Debt, Two Centuries: The Napoleonic Code Runs From 1804 to Today

A debt fell due on 1 January 2000 and was sued on 1 January 2015. Under the text of 1804 the action is alive. Under today's Code it is time-barred. Both answers come from the articles, with the chain of reasoning and a hash anyone can recompute.

A chase in profile: a round debtor in a blue scarf walks off calmly with a folded note in his pocket; behind him a small dog, then an elderly creditor reaching for his collar; then a bailiff of 1804 in bicorne and tailcoat running with an enormous hourglass strapped to his back, sand still in the upper bulb; last, a bailiff of today in a grey suit and cap stands still, holding out a tiny hourglass that has run out, shrugging.

The French Civil Code is the most recognisable legal text in the world. It has been in force since 21 March 1804, it has been rewritten many times without ever being replaced, and every civil lawyer from Paris to Buenos Aires has an opinion about it. It is now also an executable model: the articles in force, pinned byte for byte to the official open data, plus the original text of 1804 as a text of its own, answering questions with the article they rest on. The hub is public at code-civil.law.arxo.io.

This article shows what that means on three cases and one reform, and then says exactly how much of the Code is covered and how to check it.

One debt, two texts

Take one claim and one filing. The debt became enforceable on 1 January 2000; the creditor sued on 1 January 2015; nothing interrupted the period in between. The same three facts are read by two texts.

The Code of 1804. Article 2262, in its original wording, prescribes all actions, real and personal, by thirty years. Thirty years from 1 January 2000 end on 1 January 2030. The action of 2015 is not time-barred. The model answers refuted to the question "is the action prescribed on 1 January 2015?", and the deciding rule cites article 2262.

Today's Code. The reform of 17 June 2008 replaced the thirty-year rule with the five-year period of article 2224. For debts that already existed, article 26 II of the reform statute says the shorter period runs from the day the statute entered into force, 19 June 2008, without the total ever exceeding the former duration. Five years from 19 June 2008 end on 19 June 2013. The action of 2015 is time-barred. The model answers established, and the deciding rule cites article 26 II together with article 2224.

One debt read by two texts: under the Code of 1804, thirty years from 1 January 2000 run to 2030 and the action of 2015 is alive; under today's Code, the five-year period of the 2008 reform runs from 19 June 2008 to 19 June 2013 and the action of 2015 is time-barred. THE CODE OF 1804 · ARTICLE 2262 · THIRTY YEARS from 2000-01-01 · thirty years · ends 2030-01-01 2000-01-01 the debt falls due 2015-01-01 the action is filed · not time-barred · art. 2262 2030-01-01 thirty years end TODAY'S CODE · ARTICLE 26 II OF THE 2008 REFORM · ARTICLE 2224 · FIVE YEARS five years 2000-01-01 the debt falls due 2008-06-19 the reform enters into force 2013-06-19 the new period expires 2015-01-01 action filed · time-barred The shorter period runs from the day the reform entered into force, and never past the former duration. Same facts, two texts, two answers. Each names its article; the page does not pick a winner.
One debt read by two texts: under the Code of 1804, thirty years from 1 January 2000 run to 2030 and the action of 2015 is alive, article 2262; under today's Code, the five-year period of the 2008 reform runs from 19 June 2008 to 19 June 2013 and the action of 2015 is time-barred, article 26 II of the reform statute with article 2224.

The collection behind the page holds three fact patterns, each under both texts: six files, eighteen questions. Change one fact and the answers move exactly as the articles say they should.

Every one of the eighteen answers is checked in three ways before it reaches the page: against expectations written from the article text, between two independent evaluators of the same model that must produce byte-identical documents, and by replaying the saved answer. The page does not pick a winner between 1804 and today. It shows two texts and what each of them does with the same facts.

La même dette, deux siècles — checked calculation in Arxo Lens

A family, two centuries

The second case is an estate. A widow, two sons, and, when the second son dies first, a grandchild. Each pattern is read by the Code of 1804 and by the living Code.

In 1804, children take by equal shares and by head under article 745, and the surviving spouse takes nothing by intestacy while relatives exist, under article 767. Two sons: one half each; the widow, nothing. Today the surviving spouse chooses under article 757 between the usufruct of the whole estate and ownership of one quarter; with the quarter taken, the sons share the rest by head under article 753, three eighths each. When the second son has died first, his child takes his place by representation in both texts: one half in 1804, three eighths today.

One family under two texts: in 1804 the two sons take one half each under article 745 and the widow takes nothing under article 767; today the widow elects one quarter under article 757 and each son takes three eighths under article 753. THE CODE OF 1804 · A WIDOW AND TWO SONS first son · one half art. 745 · by equal shares and by head second son · one half art. 745 the widow: nothing by intestacy · art. 767 the surviving spouse takes only when no relative and no natural child remains TODAY'S CODE · THE SAME FAMILY widow · one quarter art. 757 · her election first son · three eighths art. 753 · by head within the rest second son · three eighths art. 753 When the second son dies first, his child takes his place by representation in both texts: one half in 1804, three eighths today. Both answers cite their article; neither guesses the reforms in between.
One family under two texts: in 1804 the two sons take one half each under article 745 and the widow takes nothing under article 767; today the widow elects one quarter under article 757 and each son takes three eighths under article 753.
Une famille, deux siècles — checked calculation in Arxo Lens

The model does not execute the intermediate reforms of 1891, 1972 or 2001. An estate opened on 31 December 2006 is shown under the former law with a boundary that names the transitional article. That boundary is an answer, not a gap: the reader is told which text applies and why the shares displayed are today's.

The impact study the 2016 reform never had

The contract-law reform of 10 February 2016 was made by ordinance, not by a bill, so it never had the impact study that the organic law of 2009 requires of government bills. The ratification statute of 20 April 2018 then rewrote nine of the "new" articles and declared changes to twelve others interpretative.

The hub carries the study after the fact. Eighteen fictional contracts exercise the nine rewritten articles: contracts concluded before and after 1 October 2016, clauses that the 2018 wording treats differently, a hardship claim under article 1195. The world "before 2018" is not a hand-written copy of the old law: it is built by mutating the transition corridor of the model, removing the ratification statute and nothing else. Twenty-eight questions are then asked in both worlds. In ten of them the outcome changes; in eighteen it does not, and the page says which article makes the difference in each row.

The impact study built after the fact: eighteen fictional contracts are evaluated in a world without the ratification statute of 2018, built by mutating the transition corridor, and in the world with it; of twenty-eight questions, ten outcomes change and eighteen stay the same, each row naming the article. THE REFORM OF 2016 · ORDINANCE, NO IMPACT STUDY · RATIFIED AND REWRITTEN IN 2018 eighteen fictional contracts before and after 1 October 2016 · twenty-eight questions world before the statute of 2018 built by mutating the transition corridor of the model: the ratification statute removed, nothing else touched world with the statute of 2018 nine "new" articles rewritten by article 16 I, twelve others declared interpretative 10 outcomes change 18 do not Each row names the article that makes the difference. Recalculate in the browser: the hash matches the one on the page.
The impact study built after the fact: the same eighteen fictional contracts are evaluated in a world without the ratification statute of 2018, built by mutating the transition corridor, and in the world with it; of twenty-eight questions, ten outcomes change and eighteen stay the same, each row naming the article.

Everything on that page is recomputed in the browser from the pinned bytes. A "Recalculate" button rebuilds the answers and compares the hash with the one printed on the page. On the current build they match.

What the model refuses to decide

An executable Code is not a Code that decides everything. Where the text calls for an assessment, the model returns a request for the court's finding, with the article that asks for it. Fault under the law of civil liability is the standard example: in the cross-package case on fault and reparation, the question of liability comes back as requires judgment, while the question of prescription on the same facts comes back as established, because the first needs a finding of fault and the second needs only dates.

Boundaries are declared in the same way. Contract law before 1 October 2016 is outside the model; the page says "the frontier of the model, not an absence of law". Decrees, procedure, and matters delegated to other statutes are recorded article by article with the reason they are not executed. None of this is hidden in a footnote: a reader who asks the model a question outside its area gets the boundary and its reason, not silence.

How much of the Code runs

The hub is built on the LEGI open data published by the DILA under the Licence Ouverte 2.0, with a legal cut-off of 16 September 2026. The area closed on 18 September 2026 covers fourteen packages and 2,196 articles in force, from the preliminary title through obligations, contracts, special contracts, securities, property, successions, gifts and wills, matrimonial regimes, family, and the Mayotte provisions. Two further packages, persons and sale-and-lease, are outside the closed area and run their own scenarios.

Every article in the closed area carries a status. Of the 2,196, 1,590 are executable; 606 are pinned with a declared reason for not executing, such as a judicial channel, an external act, a decree or a procedural rule; one is pinned to its text without a rule of its own; none is unexplained. Below the article, 4,123 paragraphs are classified individually as rule, judicial channel, boundary or external reference.

Coverage of the closed area on 18 September 2026 by package: articles executable against articles pinned with a declared reason, thirteen packages holding articles of the Code from the preliminary title to the Mayotte provisions, 2,196 articles in all; the transitions package holds no article of the Code itself. CLOSED AREA · 18 SEPTEMBER 2026 · 2,196 ARTICLES IN FORCE · LEGI CUT-OFF 16 SEPTEMBER 2026 Preliminary title (core) 8 of 8 Prescription (code-civil) 57 of 61 Family 52 of 395 Property 182 of 201 Successions 120 of 267 Gifts and wills 233 of 233 Contracts 151 of 151 Civil liability 47 of 48 Obligations 162 of 162 Matrimonial regimes 72 of 139 Special contracts 264 of 267 Securities 223 of 223 Mayotte 18 of 41 executable article pinned, reason declared: court, other act, decree, procedure 1,590 executable · 606 pinned with a declared reason · 1 pinned without a rule · 0 unexplained. Persons and sale-and-lease sit outside the closed area and run their own scenarios.
Coverage of the closed area on 18 September 2026 by package: articles executable against articles pinned with a declared reason, for fourteen packages from the preliminary title to the Mayotte provisions, 2,196 articles in all.

Four packages are executable article for article: contracts (151 of 151), obligations (162 of 162), gifts and wills (233 of 233) and securities (223 of 223). Family law is the other extreme, 52 of 395, because most of its articles route to a judge, a civil-status officer or a decree, and the model says so for each of them rather than pretending to compute a divorce.

How to check any of it

Each answer page carries the facts, the question, the status, the chain of rules down to the article, and the hash of the evaluation document. The Verify page reloads a saved answer and recomputes it in the browser; it either matches or shows where it does not. The text reader shows the current LEGI text and the 1804 text with the modelled provisions highlighted. The date calculators count limitation periods and forced-heirship shares from dates the reader supplies. Two evaluators of the same model, one in Rust and one in Python, must produce the same bytes for every scenario in the corpus before a build ships.

Earlier work put parts of civil codes into logic programs, PROLEG on the Japanese Civil Code being the best known, and Catala has shown how far verified compilation carries French tax and benefit law. What the Code civil hub adds is the Code itself as a running canon: the text in force and the text of 1804, pinned to their official bytes, answering with articles from both.

Arxo executes the canon. Models formalize; Arxo executes and proves.

Sources: Code civil, articles 2224, 2231, 2240, 745, 753, 757, 767, 1195 and article 2262 in its 1804 wording, LEGI open data, DILA, Licence Ouverte 2.0; loi n° 2008-561 du 17 juin 2008, article 26; ordonnance n° 2016-131 du 10 février 2016; loi n° 2018-287 du 20 avril 2018, article 16; Satoh et al., "PROLEG: An Implementation of the Presupposed Ultimate Fact Theory of Japanese Civil Code by PROLOG Technology", JSAI-isAI 2010; Merigoux, Chataing, Protzenko, "Catala: A Programming Language for the Law", ICFP 2021. Hub: code-civil.law.arxo.io.