Aids to Searching Caselaw

The development of computers changed and enhanced the searching of caselaw.

In 1971 a study of the application of computers to legal research was undertaken by the Federal Department of Justice and the Canadian Bar Association. The study was completed in April 1972 and the opening paragraphs of the report were as follows:

This study referred to as ‘Operation Compulex’was undertaken at the initiative of the Federal Department of Justice and the Canadian Bar Association. The Bureau of Management Consulting of the Federal Government was engaged to carry out the inquiry which began in June of 1971 and terminated in April 1972.

What was the reason for this inquiry? Both the Department of Justice and the Canadian Bar Association were interested in investigating whether technological developments in the information field might be of assistance to the practicing lawyer. The purpose of the inquiry then, was to determine if the practicing lawyer is experiencing difficulties with his current manual approach to dealing with information and if so, how developments in information technology might be of assistance to him.

The report comprised 54 pages plus 34 pages of appendices.

At page 30 the report states that legal research “is necessary for only some 20% of all matters referred to lawyers”

At page 17 the report stated “Indexing was the most frequent complaint by lawyers …. . Invariably when a complaint was lodged the lawyer would recommend the West Key system in the same breath.” The lawyers also wanted comprehensive cross referencing.

As a result of the recommendations in the Operation Compulex report, our firm, Maritime Law Book, commenced a key number system for its caselaw reporters similar to the West Key Number System.

This is where I start to sound like a shill.

The MLB system includes over 150 topics, beginning with Actions and ending with Workers’Compensation. All points in a case are assigned a topic name and a number. For example, Practice 651 is reserved for points in cases that describe the circumstances when a plaintiff may be added in a civil action.

In a system with over 150 topics, a sub-topic or a title may be situated in a place in the hierarchy that the searcher does not expect. For example, the title Unjust Enrichment is found in several topics. This problem is now addressed both in print and digitally on our web site. In print, MLB publishes the Master Key Word Index which provides cross-references to all titles, topics and subtopics. On the MLB web site a searcher can search the content of all 150 topics by using words such as “unjust enrichment” which results in a list of the titles or topics where “unjust enrichment” is found.

Any case, particularly an appeal case, may contain several different points of law. In addition, the MLB editors are trained to pick up and describe points in four areas that may arise in any type of case. The four areas are, professional conduct, practice, evidence and statutory interpretation.

MLB editors have created over 30,000 key numbers and as the law evolves new numbers are added.

Is there a better system for the search and retrieval of Canadian caselaw?


  1. It sounds to me like a 150-path labyrinth between the user and the information they want…

  2. “Is there a better system for the search and retrieval of Canadian caselaw?” In my opinion, no – this is the best option out there.

    If this study were re-done today, what percentage of matters referred to lawyers do you think would be found to require legal research? I suppose it depends how narrowly or broadly you define “research”, but I would venture to guess that it would be much higher than 20%.

  3. I have always appreciated the MLB Topic and key number system. When I was new in the law library, it helped to educate me about the language of the law, what concepts were related to others, and sometimes how the legal system worked.

    “For example, the title Unjust Enrichment is found in several topics.”
    It is really nice to know where Unjust Enrichment does not appear. The usefulness of the system is broader than you might expect.

    As someone not so new to law libraries, I really appreciate how it has evolved with technology – hyperlinked Key Numbers are awesome.

    Thanks for all the continuing hard work on this useful tool!

  4. Eric, for years I’ve sung to students the praises of MLB key number system and Master Key Word Index. I find it’s an excellent teaching tool as well as a functionally important resource. I believe it continues to be important for legal research instructors and librarians to remember MLB, in the shadow of the larger research databases.

    The Key Number System demonstrates well the heirarchical structure of the way we think about common law in Canada. This, of course, is in addition to offering entry points to case law on identified topics. When I was a practicing research lawyer, MLB was my go-to resource for particular issues and I taught it to students as such.

  5. Is there a better system for the search and retrieval of Canadian case law? I would say no.

    In addition to having a coherent structure and an easy to use numbering system, with key words for every principle of law considered in a case. MLB has had the benefit of focussing on reported cases and a loyal team of editors who have seen the project through pretty much from the time that the MLB law reports were first published. How could it be otherwise?