Legal Thesaurus

A legal Thesaurus is an effective tool for the organization of legal materials. The UNCITRAL Thesaurus on the CISG,[1] provides a helpful outline of the contents of each Article of the Sales Convention. The Roget’s Thesaurus provides a list of synonyms. But they are not a controlled vocabulary, containing all the possible preferred terms and displaying the semantic relationships between the terms (preffered or not).

An uncontrolled vocabulary is essentially a list of words and phrases. This list can be drawn from the information that is to be classified. Uncontrolled vocabularies lack structure and do not provide a mechanism to deal with the challenges that exist in the creation of a multilingual, international vocabulary, a vocabulary that must be released from the confines of domestic legal connotations.

Creation of Legal Thesaurus

A legal controlled vocabulary or thesaurus can be created using either:

  • a deductive method (terms are extracted from documents, but no control over the terms is made until enough terms are gathered, and then relationships are assigned) or
  • an inductive method (terms are selected as they are encountered in documents; vocabulary control and relationships are applied at the outset).[2]

A thesaurus becomes most useful when case law, scholarly commentaries and legislative history materials are indexed together for information retrieval. All these documents can be classified under preferred terms (assigned to different legal instruments, as appropriate) are then used in the index.

Some non-preferred terms may be a preferred term (prescriptor) in the thesaurus to categorize similar information on topics relating to other sources, but with a different scope note defining its usage in these contexts.[3]

The legal thesaurus can ensure that all information is “tagged”using the same terms, helping lawyers to associate and categorize particular terms. Daniel P. Dabney, in his article, The Curse of Thamus: An Analysis of Full-Text Legal Document Retrieval, wrote:

“Another effect of subject authority control [thesaurus control] in indexing may be an influence on the substantive development of the subject of the collection. For example, some of the terms that might be used as subject headings have connotations that implicitly comment on the subject matter so indexed. Consider, for example, that generations of lawyers and judges have found law relating to employment relations under the heading “Master and Servant.”This subject heading no doubt seemed reasonable to the legal community of the turn of the century when the heading was incorporated into the West Key Number System . A different segment of the society of that period might have found it reasonable to put such material under the heading “Toiler and Leech,”and colored fruitful perception of the topic in a different way. “Toiler and Leech”seems outrageous to us; “Master and Servant”seems merely archaic, but this is to a large extent the effect of familiarity. . . . The precoordination of subject headings in a thesaurus also may affect the development of the literature by making it appear that certain ideas go together and others do not.”[4]


1. See supra note 65.

2. National Information Standards Organization, Guidelines for the Construction, Format and Management of Monolingual Thesauri, ANSI/NISO Z39.19-1993 at 27.

3. See the Addendum to this Article for further comments on thesaurus treatment of “avoidance”and “termination”under the CISG and the UNIDROIT Principles and PECL.

4. Daniel D. Dabney, The Curse of Thamus: An Analysis of Full-Text Legal Document Retrieval, 78 Law Libr. J. 5, fn. 8 (1986)

See Also

Further Reading

Paul Miller, I Say What I Mean, But Do I Mean What I Say? Ariadne Issue 23 <>.

“How Do I Build a Thesaurus” <> (prepared specifically for American Society of Indexers web site) for information on the top-down and bottom-up methodologies for thesaurus construction.

National Information Standards Organization, Guidelines for the Construction, Format and Management of Monolingual Thesauri, ANSI/NISO Z39.19-1993.

Documentation – Guidelines for the establishment and development of multilingual thesauri, ISO 5964 (1985).

Barbara Bintliff, From Creativity to Computerese: Thinking Like a Lawyer in the Computer Age, 88 Law library Journal 338, 346 (1996).





References and Further Reading

About the Author/s and Reviewer/s

Author: international

Mentioned in these Entries

Cataloging for legal materials, European Thesaurus on International Relations and Area Studies, Key Number System, Law library, Linked Data Principles to Legal Information, Moys Classification and Thesaurus for Legal Materials, Thesaurus.



, ,



Leave a Reply

Your email address will not be published. Required fields are marked *