I found an article about the citations rules in English law and actually there is no national citation standard-setting authority. For most law writing, the relevant citations norms are set by widely accepted professional usage. There is also a manual written by editors of four american law journals, which is called "The Bluebook". In fact, this book shaped the citation education and resulting citation habits of most U.S. lawyers.

In the 80's a book called "Maroon Book" was published. It offered a distinctly different and less rigid set of rules, but it failed to achieve a significant following or affect professional practice. The truth is that courts not only shape local citation norms by local rules governing brief format. What is more, some courts, including both the Supreme Court and court systems in some states, retain full editorial responsability for citable, final and official versions of their opinions.

Nowadays, most of " legal citation ", like most of any language, is established by evolving usage, reinforced in some cases, altered in others, by the members of distinct communities.






NEUTRAL CITATION IN TREATIES AND RELATED DOCUMENTS.
I searched about this in the Australian Government and i found that the Commonwealth Government has adopted the medium neutral citation system for the Australian Treaties Series on both the Australian Treaties Database (ATD, wich is on the DFAT website ) and the Australian Treaties Library (ATL). Under this system a unique three-part identifier (citation) is assigned to the full name of each new treaty record. This allows users to find exact references to individual treaties and this citation can be used as a search term for locating references to this document in other legal materials (where this citation has been inserted).
The citation have got this format:
[<year of publication>] <designator> <sequential number>
Eg:
Convention on the Safety of United Nations and Associated Personnel (New York, 9 December 1994)" is cited as
Convention on the Safety of United Nations and Associated Personnel (New York, 9 December 1994) **[2001] ATS 3**

But sometimes some treaty texts refer to other treaties. To maximise the efficiency of both the ATD and the ATL, the Treaties Secretariat would be grateful if in future, such references could be accompanied by the relevant identifyer.
For example the:
Agreement Between the Government of Australia and the Government of the Arab Republic of Egypt Regarding Cooperation on Protecting the Welfare of Children
(Cairo, 22 October 2000)
Australian Treaty Series
**[2002] ATS 3**
Abbreviations:
ATS = Australian Treaty Series