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Extraction of Legal Definitions from a Japanese Statutory Corpus -- Toward Construction of a Legal Term Ontology. Makoto Nakamura, Yasuhiro Ogawa and Katsuhiko Toyama (Nagoya University). First of all. There wasn’t an English version of Japanese statutes until 2009.
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Extraction of Legal Definitions from a Japanese Statutory Corpus-- Toward Construction of a Legal Term Ontology Makoto Nakamura, Yasuhiro Ogawa and Katsuhiko Toyama (Nagoya University)
First of all • There wasn’t an English version of Japanese statutes until 2009. • Some companies have their own database as the need arises...
Japanese Law Translation Database (JLT) • Released in 2009. • Advanced user interface • Problems • quantity • quality
Problems of JLT • Quantity • 307/7,700 laws so far (<4%) (2009-2013) • Revision control wrt amendment laws • Quality • A number of translators • Disunity of translation • law titles, legal terms, etc. • specific expressions
Example: Law Titles 一般社団法人及び一般財団法人に関する法律 (ippanshadanhoujinoyobiippanzaidanhoujinnikansuruhouritsu) • Act Concerning General Corporations and General Foundations • Act on General Associations and Foundations • Act on General Associations and Incorporated Foundations • Act on General Incorporated Association and General Incorporated Foundation • Act on General Incorporated Associations and General Incorporated Foundations Insurance Business Act (Act No.105 of 1995) Article 148 (4) The provisions of Article 78 (Liability for Damages Pertaining to the Actions of the Representative) of the Act on General Incorporated Associations and General Incorporated Foundations shall apply mutatis mutandis to an Entrusting Company......
Example: Variations of Translations この法律は、公布の日から施行する。 (konohouritsuwakoufu no hi karashikousuru.) • This Act shall be enforced from the date of promulgation. • This Act shall come into effect as from the date of promulgation. • This Act shall come into effect as of the date of promulgation; • This Act shall come into effect as of the day of its promulgation. • This Act shall come into effect on the day of promulgation. • This Act shall come into force as from the date of its promulgation. • This Act shall come into force as from the day of its promulgation. • This Act shall come into force as of the date of its promulgation. • This Act shall come into force as of the day of promulgation. • This Act shall come into force from the day of promulgation. • This Act shall enter into force on the day of its promulgation.
Problem of Quality • Law titles in different ways for citation • A variety of translations An identical expression should have an identical translation for the sake of the conservation of meaning. Need of a translation dictionary
Translation tools • Terminology (dictionary) • unification of translation • 4,482 entries at the latest version • Ontology • systematic translation • Translation Memory (Sekine et al., 2012) • Statistical Machine Translation (Ogawa et al., 2013) Tomorrow!!
Purpose • to construct a legal term ontology • to provide legal terms and their explanations Approach • automatic extraction • application of natural language processing
Problems in This Study • What are legal terms? • Difficulty of Japanese text processing in the legal domain • Absence of a statutory corpus
1. What Are Legal Terms?Classification • Law titles • Legal definitions • Words in definitions • Important terms • frequently used content words • characteristic words • All words in laws Our target
1. What Are Legal Terms?Legal Definitions • are explicitly defined in a law. • consist of tuples of a defined term and its explanation. ガス事業法(昭和二十九年法律第五十一号) 第二条この法律において「一般ガス事業」とは、一般の需要に応じ導管によりガスを供給する事業をいう。 Gas Business Act (Act No.51 of 1954) Article 2 The term “General Gas Utility Business” as used in this Act shall mean the business of supplying gas via pipelines to meet general demand.
2. Difficulty of Japanese Legal Text Processing • NLP tools: low performance • special terms • syntactic rules peculiar to the legal domain • outdated characters • Simple methods for surface pattern recognition: sufficient • frequent use of boilerplate expressions
3. Compilation of aJapanese Statutory Corpus • includes all of the Japanese statutes • consists of 9,915 acts that have been enacted up to 2012 since promulgation of the new constitution of Japan in 1947 • includes OCR errors • doesn’t follow • error correction, or • consolidation by amendment laws
Solutions of the Problems • What are legal terms?→ We focus on legal definitions. • Difficulty of Japanese text processing in the legal domain→ Simple methods work effectively. • Absence of a statutory corpus→ We compiled a large corpus.
Extraction Method • Simple pattern match from a legal text • for independent sentences for definition • a sentence for definition • itemization • for expressions parenthesized in a sentence • an expression for definition • the region of its explanation
a) Example of Surface Pattern Rules Pattern of Definitions (6 rules) /「(.+)」とは、(.+)(を、|をいい、|をいう。|といい、|という。|とする。)/ /”(.+)” (as used in this Act)? (shall mean|means) (.+)./ Input text: ガス事業法 第二条この法律において「一般ガス事業」とは、一般の需要に応じ導管によりガスを供給する事業をいう。 10この法律において「ガス事業」とは、一般ガス事業、簡易ガス事業、ガス導管事業及び大口ガス事業をいう。 Gas Business Act Article 2-1 The term “General Gas Utility Business” as used in this Act shall mean the business of supplying gas via pipelines to meet general demand. Article 2-10 The term “Gas Business” as used in this Act shall mean a General Gas Utility Business, Community Gas Utility Business, Gas Pipeline Service Business or Large-Volume Gas Business.
a) Example of Surface Pattern Rules Pattern of Definitions (6 rules) /「(.+)」とは、(.+)(を、|をいい、|をいう。|といい、|という。|とする。)/ /”(.+)” (as used in this Act)? (shall mean|means) (.+)./ Input text: ガス事業法 第二条この法律において「一般ガス事業」とは、一般の需要に応じ導管によりガスを供給する事業をいう。 10この法律において「ガス事業」とは、一般ガス事業、簡易ガス事業、ガス導管事業及び大口ガス事業をいう。 Gas Business Act Article 2-1 The term “General Gas Utility Business” as used in this Act shall mean the business of supplying gas via pipelines to meet general demand. Article 2-10 The term “Gas Business” as used in this Act shall mean a General Gas Utility Business, Community Gas Utility Business, Gas Pipeline Service Business or Large-Volume Gas Business.
a) Example of Surface Pattern Rules for Itemization Pattern of Definitions for Itemization (8 rules) /(次|左|式)(の(各号|いずれか))?に(掲げる|定める)/ /the following/ Input text: 介護保険法 第七条6この法律において「医療保険各法」とは、次に掲げる法律をいう。 健康保険法 船員保険法 ・・・ Long-Term Care Insurance Act Article 7 (6) The term “Medical Insurance Acts” as used in this Act meansthe following acts: Health Insurance Act Seaman’s Insurance Act .....
b) Example of Surface Pattern Rules for Parenthesized Definitions Pattern of Parenthesized Definitions /((.+?)「(.+)」と(いう。|総称する。))/ /((.+?) referred to as “(.+)”)/ Input text: 民事訴訟法 第三十条4第一項又は前項の規定により原告又は被告となるべき者を選定した者(以下「選定者」という。)は、その選定を取り消し、又は選定された当事者(以下「選定当事者」という。)を変更することができる。 Code of Civil Procedure Article 30 (4) Persons who have appointed a party to stand as a plaintiff or defendant pursuant to the provisions of paragraph (1) or the preceding paragraph (hereafter referred to as “appointers”) may rescind the appointment or change the party thus appointed (hereafter referred to as the “appointed party”).
b) Extraction of Explanations • Extracting an explanation corresponds to finding its starting point. • Explanations are likely to start from the beginning of the sentence. • We restrict our target to extraction of explanations satisfying this condition. Easy! 民事訴訟法 第三十条4第一項又は前項の規定により原告又は被告となるべき者を選定した者(以下「選定者」という。)は、その選定を取り消し、又は選定された当事者(以下「選定当事者」という。)を変更することができる。 Difficult! If there is a parenthesis for a definition within 120 letters from the beginning without a comma or period, its explanation is from the beginning to the last letter before the parenthesis.
Experiments • Extraction of legal terms and their explanations from: • independent sentences for definition • parenthesized expressions in a sentence • The statutory corpus • 3,131 / 9,915 statutes • w/o all laws concerning amendment and repeal of pre-existing laws • Evaluation: precision and recall
Evaluation Method Statutory Corpus • Legal terms • as precise as possible • as many as possible • Evaluation • Precision • Recall Grey: the search space A: system’s response B: actual legal terms C: correct answers B A C
Experimental Result Multiple defined terms
A Semantic Network of Inclusive relations Electric Facilities for Private Use Electric Facilities Electric Facilities for General Use General Electricity Business Company Electricity Business General Electricity Business Electricity Utility Wholesale Electricity Business General Electricity Utility Wholesale Electricity Utility Designated Electricity Utility
Conclusion and Future Work • Legal terms and their explanations • over 14,000 terms with high precision • low recall rate for the process of parenthesis • applicable for any language • Toward legal term ontology • inclusive relation among explanations • systematic translation • Future works • anaphora resolution
Patterns of Definitions • An independent provision • An insert statement in parenthesis
Patterns of Definitions • An independent provision • An insert statement in parenthesis ガス事業法(昭和二十九年法律第五十一号) 第二条この法律において「一般ガス事業」とは、一般の需要に応じ導管によりガスを供給する事業をいう。 Gas Business Act (Act No.51 of 1954) Article 2 The term “General Gas Utility Business” as used in this Act shall mean the business of supplying gas via pipelines to meet general demand.
Patterns of Definitions • An independent provision • An insert statement in parenthesis ガス事業法(昭和二十九年法律第五十一号) 第四十二条ガス事業者又は卸供給事業者(以下「ガス事業者等」という。)は、その事業のように供するため、... Gas Business Act (Act No.51 of 1954) Article 42 A Gas Utility Service Provider or a Wholesale Gas Business Supplier (these persons shall hereinafter be referred to as a “Gas Utility, etc.”) may, when it is necessary to install pipelines on or under a road, bridge, ditch, river, embankment or other public land in order to use such pipelines for the businesses, use them with permission from the administrator thereof to the extent that such use does not impair their usability.
a) Independent Sentence for Definition ガス事業法(昭和二十九年法律第五十一号) 第二条この法律において「一般ガス事業」とは、一般の需要に応じ導管によりガスを供給する事業をいう。 Gas Business Act (Act No.51 of 1954) Article 2 The term “General Gas Utility Business” as used in this Act shall mean the business of supplying gas via pipelines to meet general demand.
a) Independent Sentence for Definition ガス事業法(昭和二十九年法律第五十一号) 第四十二条ガス事業者又は卸供給事業者(以下「ガス事業者等」という。)は、その事業のように供するため、道路、橋、みぞ、河川、堤防その他公共の用に供せられる土地の地上又は地中に導管を設置する必要があるときは、その効用を妨げない限度において、その管理者の許可を受けて、これを使用することができる。 Gas Business Act (Act No.51 of 1954) Article 42 A Gas Utility Service Provider or a Wholesale Gas Business Supplier (these persons shall hereinafter be referred to as a “Gas Utility, etc.”) may, when it is necessary to install pipelines on or under a road, bridge, ditch, river, embankment or other public land in order to use such pipelines for the businesses, use them with permission from the administrator thereof to the extent that such use does not impair their usability.
a) Independent Sentence for Definition 武力攻撃事態における捕虜等の取り扱いに関する法律(平成十六年法律第百十七号) 第四十二条宗教要員等(宗教要員及び第六十九条の規定により第六十四条第四号に掲げる業務に従事することを許された捕虜をいう。第八十四条第三項において同じ。)は、捕虜収容所内に置いて,被収容者の行う第四十条に規定する宗教上の行為を補助し,又は前条第一項に規定する宗教上の儀式を行うことができる。 Act on Treatment of Prisoners of War and Other Detainees in Armed Attack Situations (Act No.117 of 2004) Article 42 In the prisoner of war camp, chaplains, etc. (i.e. chaplains, and prisoners of war who are permitted to engage in works listed in item (iv) of Article 64 pursuant to the provision of Article 69. The same shall apply in paragraph (3) of Article 84) may assist the detainees in performing religious acts prescribed in Article 40 and may perform the religious ceremonies prescribed in paragraph (1) of the preceding Article.
a) Independent Sentence for Definition 武力攻撃事態における捕虜等の取り扱いに関する法律(平成十六年法律第百十七号) 第百八条2審査会は、資格認定審査請求をしたもの(以下「資格認定審査請求人」という。)が前項の期間内に補正をしないときは、裁決をもって、資格認定審査請求を却下することができる。ただし、その不適法が軽微なものであるときは、この限りでない。 Act on Treatment of Prisoners of War and Other Detainees in Armed Attack Situations (Act No.117 of 2004) Article 108 (2) In the case that a person who has appealed for a review on the recognition of internment status (hereinafter referred to as “the applicant of the appeal for review on the recognition of internment status”) fails to correct the defect within the period set forth in the preceding paragraph, the Review Board may dismiss the appeal for review on the recognition of internment status by determination; provided, however, that this shall not apply when such defect is minor.