The Business Rules Group (BRG) has played a central role in developing core notions of business rules and the business rule approach in its current form.  This discussion examines the main themes in the BRG's thinking on business rules as explicitly expressed in four highly-influential work products.  It also reveals how that thinking has been refined since the early days in 1989.

The Business Rules Group 1995 Report "Defining Business Rules ~ What Are They Really?"

The Business Rules Group 1995 Report "Defining Business Rules ~ What Are They Really?" is commonly cited as the seminal paper for business rules.  The paper gave the first authoritative definition for business rule:  "... [A] statement that defines or constrains some aspect of the business ... [which is] intended to assert business structure, or to control or influence the behavior of the business."^[1]

Although the sense of this early definition was largely correct, from today's perspective it was off-target in at least two subtle but important ways:

• A business rule is not the statement, but rather the meaning of the statement.  For example, a business rule expressed in two or more languages (e.g., English, French, Mandarin) is still the same business rule.  This important distinction was properly addressed by more recent work on "Semantics of Business Vocabulary and Business Rules" (SBVR).
  
  
• Terms and facts "assert business structure" but they are not rules.  It is misleading to say business rules "assert business structure."  Instead, rules provide guidance and shape behavior and decisions.  SBVR also rectified this representation.

The paper shows several notable differences with expert systems:

• A data-model and database orientation.
  
• A focus on rules that people can break.

BRG explicitly acknowledged that this early work on business rules was from an information system (IS) perspective.  It identified the business perspective as being the proper focus for its subsequent work.

Origins of the Business Rules Group (BRG) The BRG's origins trace to 1989.[2] [3]  Originally a project within GUIDE International, the BRG became an independent organization in 1997.  Membership comprised experienced practitioners in the field of information systems and business analysis from both the public and the private sectors. The BRG was chartered to formulate statements and support standards about the: nature and structure of business rules. relationship of business rules with the way an enterprise is organized. relationship of business rules with system architecture. The paper explains the BRG's mission of as follows: "Information Systems analysts have long been able to describe an enterprise in terms of the structure of the data the enterprise uses and the organization of the functions it performs.  Unfortunately, there is often neglect of the rules … under which the enterprise operates.  Frequently these rules are not articulated until it is time to convert them into program code.  While rules that are represented by the structure and functions of an enterprise have been documented to a degree, others have not been articulated well, if at all.  The Business Rules Group was organized to carry out that articulation."

The Business Rules Manifesto

The clearest and most succinct statement of the principles for the business rules approach is the Business Rules Manifesto,^[4] a 2003 work product of the BRG. The Manifesto is now available in 18 languages.

The purpose of the Manifesto was to "provide a clear, concise — and relatively brief — statement of the business rule 'message'" and to "declare independence for rules in the world of requirements and models".^[5]  Principle 1.1 declares "Rules are a first-class citizen of the requirements world."

The Manifesto clearly reflects core thinking of the BRG. Principle 2.1 states "Rules are explicit constraints on behavior and/or provide support to behavior".  Principle 3.1 expresses "Rules build on facts, and facts build on concepts as expressed by terms."

The relationship to the Business Motivation Model (BMM) is expressed by Principle 8.1, "Rules are about business practice and guidance; therefore, rules are motivated by business goals and objectives and are shaped by various influences."

The relationship to Semantics of Business Vocabulary and Business Rules (SBVR) is expressed by several Principles, among them:

• 4.1  Rules should be expressed declaratively in natural-language sentences for the business audience.
  
  
• 5.3  Formal logics, such as predicate logic, are fundamental to well-formed expression of rules in business terms, as well as to the technologies that implement business rules.

The relationship to knowledge is expressed by Principle 3.4, "Rules are basic to what the business knows about itself — that is, to basic business knowledge."

The Business Motivation Model

In 2003, the BRG released "Business Motivation Model (BMM):  Business Governance in a Volatile World."^[6]  The BMM provides a rich vocabulary and guide to strategy and a basis for understanding the motivation for business rules.  In terms of the Zachman Framework it is characterized as reflecting 'row 2', column 6 ('motivation').  In 2008, the Object Management Group (OMG) published the work in UML as a standard.

Motivation indicates why an enterprise has the business rules it has put in place to govern what it does.  The BMM is based on two fundamental ideas:

• Ends and Means.  Among the ends are things the enterprise wishes to achieve — for example, goals and objectives.  Among the means are things the enterprise will employ to achieve those ends — for example, strategies, tactics, business policies, and business rules.
  
  
• Influencers shape the elements of the business strategies, and the assessments made about the impacts of such influencers on ends and means (i.e., strengths, weaknesses, opportunities, and threats).

The BMM indicates both business policies and business rules to be directives.  A business policy is defined as:

"a directive concerned with directly controlling, influencing, or regulating the actions of an enterprise and the people in it and that is not directly enforceable.  Compared to a business rule, a business policy tends to be:

• less structured.
• less discrete.
• less atomic.
• less compliant with standard business vocabulary.
• less formally articulated."

A business policy can provide the basis for business rules.

The BMM introduced the key notion that a business rule is practicable.  'Practicable' means that "a person who understands a directive could observe a relevant situation (including his or her own behavior) and recognize directly whether or not the business was complying with that directive."  In other words, a business rule is ready to deploy into business operations.  The BMM adopts its actual definition of business rule from SBVR.

Semantics of Business Vocabulary and Business Rules (SBVR)

Starting in 2003, the Business Rules Group initiated work on structuring the business vocabulary underlying business rules, based the mantra it had become known for:  terms, facts, and rules — rules build on facts, and facts build on terms.  This work culminated in the January 2008 release by the Object Management Group (OMG) of the first standard for business rules, "Semantics of Business Vocabulary and Business Rules" (SBVR) 1.0.^[7]

SBVR defines business rule as a "rule that is under business jurisdiction."

Under business jurisdiction means that "it is under the jurisdiction of an authority that can opt to change or discard the rule at its own discretion."

A rule is defined as "a proposition that is a claim of obligation or of necessity."  SBVR emphasizes the common sense understanding of 'rule' — "a rule always tends to remove some degree of freedom."

The SBVR definition for rule is deeply embedded in formal logic and propositions.^[8]  In modal logic, propositions can claim different modes.  For business rules the two relevant modes are alethic and deontic.

• Alethic rules, called definitional rules or structural rules in SBVR, are established by claiming necessity.  They are true 'by definition'.   As such they cannot be violated.  They are about how concepts, knowledge, or information are defined or structured.
  
  
• Deontic rules, called behavioral rules or operative rules in SBVR, are established by claiming obligation.  They are rules that can be violated — rules about behavior, not concepts, knowledge, or information.  Deontic rules are really about people, what they must and must not do, even if their activity (and the rules) are automated.

The separation of alethic vs. deontic rules by SBVR reflects the BRG's longstanding emphasis on rules that people can break, a fundamental reality of running any business.

References

[1]  "Defining Business Rules ~ What Are They Really?" (formerly known as the "GUIDE Business Rules Project Report," 1995), edited by David C. Hay and Keri Anderson Healy, pp. 4-5.  

[2]  Editors of BRCommunity.com, "A Brief History of the Business Rule Approach, 3rd ed.," Business Rules Journal, Vol. 9, No. 11 (November 2008), Section 3.  URL:  http://www.BRCommunity.com/a2008/b448.html  

[3]  "About the BRG," BusinessRulesGroup.org, at:  http://www.businessrulesgroup.org/groupbrg.shtml  

[4]  The Business Rules Manifesto:  Principles of Rule Independence, Version 2.0, edited by Ronald G. Ross.  The Business Rules Group (November 1, 2003).  Available at:  http://www.businessrulesgroup.org/brmanifesto.htm  

[5]  Editors of BRCommunity.com, "A Brief History of the Business Rule Approach, 3rd ed.," Business Rules Journal, Vol. 9, No. 11 (November 2008), Section 4. URL:  http://www.BRCommunity.com/a2008/b448.html  

[6]  The Business Motivation Model:  Business Governance in a Volatile World, edited by John Hall, Keri Anderson Healy, and Ronald G. Ross, May, 2010, Release 1.4.  Available at:  http://www.businessrulesgroup.org/bmm.shtml.  This work was first released in 2003 under the name "Organizing Business Plans - The Standard Model for Business Rule Motivation", then given its current name in 2005.  

[7]  Semantics of Business Vocabulary and Business Rules (SBVR), (Version 1.0).  Object Management Group (January 2008).  Available at:  http://www.omg.org/spec/SBVR/1.0/  

[8]  Ronald G. Ross, "The Two Fundamental Kinds of Business Rules:  Where They Come From and Why They Are What They Are," Business Rules Journal, Vol. 15, No. 11 (Nov. 2014), URL:  http://www.BRCommunity.com/a2014/b783.html  

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