A neutral citation is the unique reference given to a particular judgment by HM Courts and Tribunals Service. Unlike the majority of citations, neutral citations do not refer to a specific report of a case, but to the judgment itself. A neutral citation by itself therefore cannot be used to locate a law report without further research; however, it is particularly useful when citing or tracing an unreported case.
Neutral citations were introduced in 2001. No official neutral citations exist for cases before 2001, although BAILII has attributed its own unofficial neutral-style citations to earlier cases. Holborn describes the introduction as follows:
“… as a consequence of the much wider availability of unreported cases from electronic sources, and because of electronic promulgation of law reports series, the Lord Chief Justice issued on 11 January 2001 the Practice Direction (Judgments: Form and Citation)  1 W.L.R. 194. This introduced three matters: the provision of a court-assigned number for every judgment; paragraphing of judgments; and the authorisation of the citation before the courts of reported cases derived from an electronic version of the reports. The first two innovations together provide a so-called ‘neutral citation’, which uniquely identifies a case, and a passage in it, whether or not it is reported. This comprises the year, an abbreviation for the court, the number of the case, and then any reference to a particular paragraph in square brackets. Thus:
Smith v Jones  EWCA Civ 10 at 
This refers to case no 10 of the Court of Appeal (Civil Division) – EW for England and Wales – of 2001 and a passage at para 30. The Practice Direction initially applied to judgments of the Court of Appeal, Civil and Criminal Divisions, and the Administrative Court (Queen’s Bench cases on judicial review, etc). It is to be extended in due course to the other Divisions of the High Court. The House of Lords has also adopted the practice – its abbreviation is UKHL, reflecting its wider jurisdiction.”
(Guy Holborn, Butterworths Legal Research Guide, 2nd edition, 2006, p.187.)
The text of the relevant Practice Direction can be seen below:
“Practice Direction (Sup Ct: Judgments: Form and Citation)
11 January 2001
 1 W.L.R. 194
Neutral Citation of Judgments
2.1 With effect from 11th January 2001 a form of neutral citation will be introduced in both divisions of the Court of Appeal and in the Administrative Court. A unique number will be given by the official shorthand writers to each approved judgment issued out of these courts. The judgments will be numbered in the following way:
Court of Appeal (Civil Division)  EWCA Civ 1, 2, 3 etc.
Court of Appeal (Criminal Division)  EWCA Crim 1, 2, 3 etc.
High Court (Administrative Court)  EWHC Admin 1, 2, 3 etc.
2.2 Under these new arrangements, paragraph 59 in Smith v Jones, the tenth numbered judgment of the year in the Civil Division of the Court of Appeal, would be cited:
Smith v Jones  EWCA Civ 10 at 
2.3 The neutral citation will be the official number attributed to the judgment by the court and must always be used on at least one occasion when the judgment is cited in a later judgment. Once the judgment is reported, the neutral citation will appear in front of the familiar citation from the law reports series. Thus:
Smith v Jones  EWCA Civ 10 at ,  QB 124,  2 All ER 364, etc.
The paragraph number must be the number allotted by the court in all future versions of the judgment.
2.4 If a judgment is cited on more than one occasion in a later judgment, it will be of the greatest assistance if only one abbreviation (if desired) is used. Thus Smith v Jones  EWCA Civ 10 could be abbreviated on subsequent occasions to Smith v Jones, or Smith’s case, but preferably not both (in the same judgment).
2.5 If it is desired to cite more than one paragraph of a judgment each numbered paragraph should be enclosed with a square bracket. Thus:
Smith v Jones  EWCA Civ 10 at –, or
Smith v Jones  EWCA Civ 10 at , , and –
2.6 The neutral citation arrangements will be extended to include other parts of the High Court as soon as the necessary administrative arrangements can be made.
2.7 The Administrative Court citation will be given to all judgments in the Administrative Court, whether they are delivered by a Divisional Court or by a single judge.”
Format of neutral citations
Since its initial introduction, the system of neutral citations has been extended to cover more courts in addition to the Court of Appeal and the Administrative Court. Here is a list of the courts which assign neutral citations, and their format:
Neutral citations adopted from 11th January 2001:
• House of Lords: [year] UKHL number.
e.g.  UKHL 52
(NB This series of neutral citations ceased in 2009, when the Supreme Court replaced the House of Lords as the UK’s highest court of appeal.)
• Privy Council: [year] UKPC number.
e.g.  UKPC 2
o Privy Council (Devolution cases): [year] UKPC Dnumber.
e.g.  UKPC D2 (If searching on Westlaw, the search function requires users to enter a space between D and the case number, i.e.  UKPC D 2.)
• England and Wales Court of Appeal (Civil Division): [year] EWCA Civ number.
e.g.  EWCA Civ 134
• England and Wales Court of Appeal (Criminal Division): [year] EWCA Crim number.
e.g.  EWCA Crim 4
• England and Wales High Court (Administrative Court): (during 2001): [year] EWHC Admin number.
e.g.  EWHC Admin 40.
(From 2002): [year] EWHC number (Admin).
e.g.  EWHC 4 (Admin)
Neutral citations adopted from 14th January 2002:
• England and Wales High Court (Chancery Division): [year] EWHC number (Ch).
e.g.  EWHC 60 (Ch)
• England and Wales High Court (Patents Court): [year] EWHC number (Pat).
e.g.  EWHC 1373 (Pat)
• England and Wales High Court (Queen’s Bench Division): [year] EWHC number (QB).
e.g.  EWHC 13 (QB)
• England and Wales High Court (Commercial Court): [year] EWHC number (Comm). e.g.  EWHC 83 (Comm)
• England and Wales High Court (Admiralty Court): [year] EWHC number (Admlty). e.g.  EWHC 838 (Admlty)
• England and Wales High Court (Technology and Construction Court): [year] EWHC number (TCC).
e.g.  EWHC 400 (TCC)
• England and Wales High Court (Family Division): [year] EWHC number (Fam).
e.g.  EWHC 540 (Fam)
• England and Wales High Court (Mercantile Court): [year] EWHC number (Mercantile).
e.g.  EWHC 11 (Mercantile).
(NB If using Westlaw, this style of citation is not recognised; the citation is instead the same as that of Queen’s Bench judgments, i.e.  EWHC 11 (QB).)
Neutral citations adopted from 1st October 2009:
• UK Supreme Court: [year] UKSC number.
e.g.  UKSC 1
Neutral citations adopted from 22nd April 2014:
• England and Wales Family Court: [year] EWFC number.
e.g.  EWFC 4
• England and Wales Court of Protection: [year] EWCOP number.
e.g.  EWCOP 5
Several tribunals also have neutral citations; these are:
• Competition Appeal Tribunal: [year] CAT number.
e.g.  CAT 1
• Upper Tribunal (Administrative Appeals Chamber): [year] UKUT number (AAC). e.g.  UKUT 19 (AAC)
• Upper Tribunal (Immigration and Asylum Chamber): [year] UKUT number (IAC). e.g.  UKUT 57 (IAC)
• Upper Tribunal (Lands Chamber): [year] UKUT number (LC).
e.g.  UKUT 1 (LC)
• Upper Tribunal (Tax and Chancery Chamber): [year] UKUT number (TCC).
e.g.  UKUT 8 (TCC)
There are also official neutral citation systems in use for the courts of Scotland, Northern Ireland and the Republic of Ireland.
In January 2016, the Ecclesiastical Judges Association introduced neutral citations for judgments of consistory courts: http://www.lawandreligionuk.com/2015/12/28/neutral-citations-for-consistory-court-judgments/
Practice Direction (Sup Ct: Judgments: Neutral Citations) 14 January 2002.
This Practice Direction extended the practice of neutral citation to all judgments given by the High Court in London. Notes that each judgment receives a unique number, with the result that “it will be unnecessary to include the descriptive word in brackets when citing the paragraph number of a judgment”.
Reported at  1 W.L.R. 346;  1 All E.R. 351;  2 Lloyd’s Rep. 228;  1 Lloyd’s Rep. 424; Times, January 17, 2002.
Form of Decisions and Neutral Citation First-Tier Tribunal and Upper Tribunal on or after 3 November 2008.
Practice Statement produced by the Tribunals Judiciary setting out the arrangements for the neutral citation of tribunal decisions. Reported at  1 W.L.R. 871;  P.T.S.R. 545; https://www.judiciary.gov.uk/publications/form-of-decisions-and-neutral-citation/
Information about the neutral citation system from BAILII. http://www.bailii.org/bailii/citation.html
Searching by Citation on ICLR Online.
Information about legal citations from ICLR, including a section on neutral citations. http://www.iclr.co.uk/searching-citation-iclr-online/
Inner Temple Library FAQ: What is a neutral citation? https://www.innertemplelibrary.org.uk/news/FAQuk/CaseNeutral.htm