Legal writing is a type of technical writing

Technical writing

Technical writing, a form of technical communication, is a style of writing used in fields as diverse as computer hardware and software, engineering, chemistry, the aerospace industry, robotics, finance, consumer electronics, and biotechnology....

 used by lawyer

Lawyer

A lawyer, according to Black's Law Dictionary, is "a person learned in the law; as an attorney, counsel or solicitor; a person who is practicing law." Law is the system of rules of conduct established by the sovereign government of a society to correct wrongs, maintain the stability of political...

s, judge

Judge

A judge is a person who presides over court proceedings, either alone or as part of a panel of judges. The powers, functions, method of appointment, discipline, and training of judges vary widely across different jurisdictions. The judge is supposed to conduct the trial impartially and in an open...

s, legislator

Legislator

A legislator is a person who writes and passes laws, especially someone who is a member of a legislature. Legislators are usually politicians and are often elected by the people...

s, and others in law

Law

Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...

 to express legal analysis and legal rights and duties.
Legal writing places heavy reliance on authority. In most legal writing, the writer must back up assertions and statements with citation

Citation

Broadly, a citation is a reference to a published or unpublished source . More precisely, a citation is an abbreviated alphanumeric expression Broadly, a citation is a reference to a published or unpublished source (not always the original source). More precisely, a citation is an abbreviated...

s to authority. This is accomplished by a unique and complicated citation system, unlike that used in any other genre of writing. The standard methods for American legal citation

Legal citation

Legal citation is the practice of crediting and referring to authoritative documents and sources. The most common sources of authority cited are court decisions , statutes, regulations, government documents, treaties, and scholarly writing....

 are defined by two competing rulebooks: the ALWD Citation Manual

ALWD Citation Manual

The ALWD Citation Manual is a legal citation system for the United States compiled by the Association of Legal Writing Directors. Its first edition was published in 2000. Currently, it is in its fourth edition ....

: A Professional System of Citation and The Bluebook

Bluebook

The Bluebook: A Uniform System of Citation, a style guide, prescribes the most widely used legal citation system in the United States. The Bluebook is compiled by the Harvard Law Review Association, the Columbia Law Review, the University of Pennsylvania Law Review, and the Yale Law Journal....

: A Uniform System of Citation.