The European Case Law Identifier (ECLI) is an identifier for court decisions in Europe. The identifier consists of five elements separated by colons: ECLI:[country code]:[court identifier]:[year of decision]:[specific identifier]. The standard is laid down in the Council Conclusions inviting the introduction of the European Case Law Identifier (ECLI) and a minimum set of uniform metadata for case law of the European Union. The ECLI framework also contains a set of uniform metadata to improve search facilities for case law. Court decisions that have an ECLI assigned can be indexed by the ECLI Search Engine of the European e-Justice portal.

The concept of ECLI was first launched at the Legal Access Conference (Paris, December 2008) and at Jurix Conference on Artificial Intelligence and Law in Florence (December 2008). Around the same time, the study by a task group of the EU Council Working Group on e-Law showed that accessibility of judicial decisions, both at the national and European level, was seriously hampered by the lack of standardised identifiers and metadata:

The task group suggested to establish a voluntary common identification system based on the European Case-Law Identifier (ECLI). ECLI as an identifier would be linked to an index with references. This would enable any citizen or legal practitioner to find any decision to which ECLI has been attributed from any public or private register or database in the EU. In addition a Dublin-core implementation for case-law should be established to facilitate searching case-law in different search engines.

Based on the report of this task group, the Council of Ministers agreed on the principles of ECLI and common metadata, and asked the EU Council Working Party on Legal Data Processing (e-Law) to elaborate the initial work. This continued work resulted in the Council Conclusion inviting the introduction of the European Case Law Identifier (ECLI) and a minimum set of uniform metadata for case law of the European Union, decided upon by the Council of Ministers on 22 December 2010. It was published in the Official Journal of 29 April 2011 (2011/C 127/01).

ECLI does not primarily identify a paper or electronic document containing a judgment, but instead identifies the court decision at a more abstract level. In the terminology of the Functional Requirements for Bibliographic Records on which it is based, ECLI is a work-level identifier. It is constructed with the intention to be meaningful, open, technologically neutral, recognisable for both humans and computers, error-proof and interoperable with other identifiers. The formatting rules for ECLI are prescribed in detail in the Annex to the Council Conclusions. Summarized, an ECLI always consists of five parts, separated by a colon:

Only the Latin alphabet is to be used, and that ECLI is case-insensitive, although it is written preferably in capitals. An example of a case law identifier of the Dutch Supreme Court is ECLI:NL:HR:1841:1, which indicates a Dutch decision (NL) of 1841 of the Supreme Court (HR) with serial number 1.

According to paragraph 4 of the Annex to the Council Conclusions an ECLI website has to be set up, containing

The ECLI website was set up within the frame work of the e-justice portal of the European Union.