These practices are generally adopted on a court system by court system basis, rather than by individual judges.
The United States is currently in a transitional stage with regard to this issue. This is a somewhat stylized recounting of how this came to be.
Historically, cases were referred to by the volume, initial page number, and pinpoint citation page number of the material in question in a privately assembled and printed case reporter, such as "U.S. Reports" or the "Pacific Reporter." In this area, the pilcrow was used mostly in contracts and selected statutes and regulations, rather than in court opinions.
Eventually, the West Corporation came to be the dominant published of case reporters and sought to use its copyright in the page numbers of its reporters to bar other firms from entering the field of legal research and case reporting. West lost its copyright cases, but state courts nonetheless grew concerned about this tactic and their reliance upon a single privately owned company for the whole of their case law system. Further, the rise of electronic media made a paper agnostic system of case citation desirable.
Eventually state appellate courts started to adopt a publisher and "media neutral citation system." Colorado's system illustrates how these work.
Published cases are assigned a case number based upon the year it is decided, the appellate court deciding it, and the sequence of the announcement of the decision in the year. So, the 43rd case decided by the Colorado Court of Appeals in the year 2024 would have the case number 2024 COA 43, and the 12th case decided by the Colorado Supreme Court in the year 2023 would have the case number 2023 CO 12.
To facilitate pinpoint citation, courts adopting this system started to assign paragraph numbers to each paragraph of their opinion. So, a pinpoint citation to the 7th paragraph of the 12th case decided by the Colorado Supreme Court in the year 2023 would be cited 2023 CO 12, ¶ 7. Some trial courts have also started to number their paragraphs, although this practice is less uniform.
Many U.S. states and a small number of U.S. federal courts have adopted this system for cases decided on or after the year the system was adopted in that state, and this is slowly growing. In some states, judges and lawyers must use the new citation system to refer to new cases in legal documents, while in other states, it is optional and the historical methods of case citation may be used instead. As explained at the link in this paragraph (which is a slightly outdated since I believe that more courts have adopted the system since this was written in 2021):
In 1996, the American Bar Association approved a resolution
recommending that courts adopt a uniform public domain citation system
"equally effective for printed case reports and for case reports
electronically published on computer disks or network services" and
laying out the essential components of such a medium-neutral system
(see § 1-500). The American Association of Law Libraries had
previously gone on record for "vendor and media neutral" citation and
has since issued a Universal Citation Guide that details an approach
consistent with that urged by the ABA. An increasing number of
jurisdictions have adopted citation schemes embodying some or all of
the elements recommended by these national bodies. North Dakota is
representative. Its court rules state in relevant part:
When available, initial citations must include the volume and initial
page number of the North Western Reporter in which the opinion is
published. The initial citation of any published opinion of the
Supreme Court released on or after January 1, 1997, contained in a
brief, memorandum, or other document filed with any trial or appellate
court and the citation in the table of cases in a brief must also
include a reference to the calendar year in which the decision was
filed, followed by the court designation of "ND", followed by a
sequential number assigned by the Clerk of the Supreme Court. A
paragraph citation should be placed immediately following the
sequential number assigned to the case. Subsequent citations within
the brief, memorandum or other document must include the paragraph
number and sufficient references to identify the initial citation.
N.D. R. Ct. 11.6(b).
The Rule supplies examples, e.g.:
Smith v. Jones, 1997 ND 15, 600 N.W.2d 900 (fictional). Smith v.
Jones, 1996 ND 15, ¶ 21, 600 N.W.2d 900 (fictional). For decisions of
the North Dakota Court of Appeals, the formula is the same with the
substitution of "ND App" for "ND". In jurisdictions adopting such a
vendor- and medium-neutral citation scheme, that scheme should be
used, together with one or more parallel reporter citations as may,
indeed, be required by court rule or local practice.
While the formats and other details vary slightly, several other
jurisdictions have implemented case citation schemes employing the
same basic structure—case name, year, court, sequential number, and
(within the opinion) paragraph number or numbers. In addition to North
Dakota these include Colorado, Maine, Montana, New Mexico, Oklahoma,
South Dakota, Utah, Vermont, Wisconsin, and Wyoming. North Carolina
has adopted this scheme, effective as of the beginning of 2021. In
2009 Arkansas began to designate its appellate decisions in this way,
while retaining page numbers within the court-released pdf file as the
means for pinpoint cites. Four other states, Louisiana, Mississippi,
Ohio, and, most recently, Illinois, have adopted medium-neutral
citation systems, but along the significantly different lines noted
below. At the federal level, the progress has, to date, been minimal.
The U.S. Court of Appeals for the Sixth Circuit began to apply
medium-neutral file names to its own decisions in 1994, but it has
never directed attorneys to use them nor employed them itself in
referring to prior decisions that have appeared in the Federal
Reporter series. Among district courts, the District of New Hampshire
stands alone. Since 2000 some, although unfortunately not all, of its
substantive opinions have carried case designations in the format
"2020 DNH 081". The court's judges use these citations in decisions,
and local citation rules call upon lawyers to employ them as well.
Ohio's case numbering approach operates across the entire state court
system rather than court by court, with the result that successive
decisions of the state supreme court may be numbered 3957 and 3995.
(These system-wide numbers are assigned by the state's reporter of
decisions.) Illinois, Louisiana, and Mississippi use the docket number
as the case ID rather than generating a new one based on year and
decision sequence. In addition, Louisiana, like Arkansas, uses slip
opinion page numbers rather than paragraph numbers for pinpoint
citation. The U.S. Court of Appeals for the Sixth Circuit does the
same.
Most jurisdictions adopting a medium-neutral system have done so
prospectively only. Citations to cases that pre-date the change must
still employ reporter volume and page numbers. Two states, however,
have retrofitted all past reported decisions with neutral citations
and paragraph numbers. The court rules of one of them, Oklahoma,
strongly encourage the use of the print-independent citations for
those older cases, and the state’s appellate courts model the
practice. In New Mexico the neutral citation system has, since 2013,
been required for citations to opinions dating all the way back to
1852.
A few jurisdictions have moved to official electronic publication of
case reports without altering traditional volume and page number
citation. Putnam v. Scherbring, decided by the Nebraska Supreme Court
in September 2017, has been "297 Neb. 868" from the moment of its
release. The citation refers to the decision's volume and page number
in a book that will never be printed. Official publication of the
Nebraska Reports has moved online. Its volumes are now virtual. Each
decision begins a fresh page. When the page count climbs to 1,000 or
so, the next nominal volume is begun.
Cases before this system was adopted are cited in the traditional way such as 456 P.2d 587, 600 (Colo. App. 1992), so most appellate court opinions and briefs by attorneys have a mix of different citation systems in them. The portion of a case citation with the names of the parties is unchanged.
Australia has made a similar transition.
I don't know what other Anglo-sphere legal systems have done in this regard.
