International Code of Zoological Nomenclature

The International Code of Zoological Nomenclature (ICZN or ICZN Code) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. The rules principally regulate:

1. how names are correctly established in the frame of binominal nomenclature
2. which name must be used in case of conflicts among various names
3. how names must be cited in the scientific literature.

Written nomenclatural rules in zoology were compiled in various countries since the late 1830s, such as Merton's Rules and Strickland's codes going back to 1843. At the first and second International Zoological Congresses (Paris 1889, Moscow 1892) zoologists saw the need to establish commonly accepted international rules for all disciplines and countries to replace conventions and unwritten rules that varied across disciplines, countries, and languages.

Compiling "International Rules on Zoological Nomenclature" was first proposed in 1895 in Leiden (3rd International Congress for Zoology) and officially published in three languages in 1905 (French, English, German; only French was official). From then on, amendments and modifications were subsequently passed by various zoological congresses (Boston 1907, Graz 1910, Monaco 1913, Budapest 1927, Padova 1930, Paris 1948, Copenhagen 1953, and London 1958). These were only published in English, and can only be found in the reports of these congresses or other official publications.

The 1905 Rules became increasingly outdated. They soon sold out, and it became increasingly difficult to obtain to a complete set of the Rules with all amendments. In Copenhagen 1953 the French and English texts of the Rules were declared of equivalent official force, and a declaration was approved to prepare a new compilation of the rules. In 1958, an Editorial Committee in London elaborated a completely new version of the nomenclatural rules, which were finally published as the first edition of the ICZN Code on 9 November 1961.

The 2nd edition of the Code (only weakly modified) came in 1963. The last zoological congress to deal with nomenclatural problems took place in Monte Carlo 1972, since by then the official zoological organs no longer derived power from zoological congresses. The 3rd edition of the Code came out in 1985. The present edition is the 4th edition, effective since 2000. These Code editions were elaborated by editorial committees appointed by the International Commission on Zoological Nomenclature. The ICZN Commission takes its power from a general biological congress (IUBS, International Union of Biological Sciences). The Editorial Committee for the 4th edition was composed of seven persons. Such new editions of the ICZN Code are not democratically approved by those taxonomists who are forced to follow the Code's provisions, neither do taxonomists have the right to vote for the members of the Commission or the Editorial Committee.

As the Commission may alter the Code (by declarations and amendments) without issuing a new edition of the book, the current edition does not necessarily contain the actual provision that applies in a particular case. Currently the Code consists of the original text of the 4th edition and Declaration 44. The Code is published in an English and a French version; both versions are official and equivalent in force, meaning, and authority. This means that if something in the English Code is unclear or its interpretation ambiguous, the French version is decisive, and if there is something unclear in the French Code, the English version is decisive.

The Code deals with zoological nomenclature, which is defined in the Glossary as

"The system of scientific names for animal taxa and the provisions for the formation, treatment, and use of those names."

Zoological nomenclature is independent of other systems of nomenclature, for example botanical nomenclature. This implies that animals can have the same generic names as plants.

The rules and recommendations have one fundamental aim: to provide the maximum universality and continuity in the naming of all animals, except where taxonomic judgment dictates otherwise. The Code is meant to guide only the nomenclature of animals, while leaving zoologists freedom in classifying new taxa.

In other words, whether a species itself is or is not a recognized entity is a subjective decision, but what name should be applied to it is not. The Code applies only to the latter, not to the former. A new animal name published without adherence to the Code may be deemed simply "unavailable" if it fails to meet certain criteria, or fall entirely out of the province of science (e.g., the "scientific name" for the Loch Ness Monster).

The rules in the Code determine what names are valid for any taxon in the family group, genus group, and species group. It has additional (but more limited) provisions on names in higher ranks. The Code recognizes no case law. Any dispute is decided first by applying the Code directly, and not by reference to precedent.

The Code is also retroactive or retrospective, which means that previous editions of the Code, or previous other rules and conventions have no force any more today, and the nomenclatural acts published 'back in the old times' must be evaluated only under the present edition of the Code. In cases of disputes concerning the interpretation, the usual procedure is to consult the French Code, lastly a case can be brought to the Commission who has the right to publish a final decision.