A legal treatise is a scholarly legal publication containing all the law relating to a particular area, such as criminal law

Criminal law

Criminal law, is the body of law that relates to crime. It might be defined as the body of rules that defines conduct that is not allowed because it is held to threaten, harm or endanger the safety and welfare of people, and that sets out the punishment to be imposed on people who do not obey...

 or trusts and estates

Trusts and estates

The law of trusts and estates is generally considered the body of law which governs the management of personal affairs and the disposition of property of an individual in anticipation of the event of such person's incapacity or death, also known as the law of successions in civil law...

. There is no fixed usage on what books qualify as a "legal treatise," with the term being used broadly to define books written for practicing attorneys

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...

 and 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, textbooks for law students, and explanatory texts for laypersons.

Legal treatises are secondary authority

Secondary authority

In law, a secondary authority is an authority purporting to explain the meaning or applicability of the actual verbatim texts of primary authorities .Some secondary authority materials are written and published by governments to explain the laws in simple,...

, and can serve as a useful starting point for legal research

Legal research

Legal research is "the process of identifying and retrieving information necessary to support legal decision-making. In its broadest sense, legal research includes each step of a course of action that begins with an analysis of the facts of a problem and concludes with the application and...

, particularly when the researcher lacks familiarity with a particular area of law. Lawyers commonly use legal treatises in order to review the law and update their knowledge of pertinent primary authority

Primary authority

A primary authority is a document that establishes the law on a particular issue, such as a case decision or legislative act. The search for applicable primary authority is an important part of the process of legal research....

 namely, case law

Case law

In law, case law is the set of reported judicial decisions of selected appellate courts and other courts of first instance which make new interpretations of the law and, therefore, can be cited as precedents in a process known as stare decisis...

, statute

Statute

A statute is a formal written enactment of a legislative authority that governs a state, city, or county. Typically, statutes command or prohibit something, or declare policy. The word is often used to distinguish law made by legislative bodies from case law, decided by courts, and regulations...

s, and administrative regulations

Regulation

Regulation is administrative legislation that constitutes or constrains rights and allocates responsibilities. It can be distinguished from primary legislation on the one hand and judge-made law on the other...

.

In law school

Law school

A law school is an institution specializing in legal education.- Law degrees :- Canada :...

s, treatises are sometimes used as additional study materials, as treatises often cover legal subjects at a higher level of detail than most casebook

Casebook

A casebook is a type of textbook used primarily by students in law schools. Rather than simply laying out the legal doctrine in a particular area of study, a casebook contains excerpts from legal cases in which the law of that area was applied. It is then up to the student to analyze the language...

s do. Certain treatises, called hornbook

Hornbook

A hornbook is a book that serves as primer for study. The hornbook originated in England in 1450 . The term has been applied to a few different study materials in different fields...

s, are used by American law students as supplements to casebooks. Hornbooks are usually one volume - sometimes a briefer version of a longer, multi-volume treatise written by a recognized legal scholar.