Law Associates is a large legal practice based in Sydney.  You have been asked to design a data model for the practice based upon the following specification:

The practice employs nearly sixty lawyers who work in a wide variety of specialty areas. A speciality id and description is stored for each speciality. Each lawyer employed by the practice is classified as a partner, an associate, a junior or an intern. The practice stores the following information for all lawyers: Name, address, telephone, email, base salary and the one area of law in which that lawyer specialises.. For partners, the practice also stores information about the percentage of the partnership held by the lawyer and the area of speciality that lawyer leads. Each area of speciality has one partner who acts as a leader (or resident expert and consultant) in that area. For associates, the practice also stores details about the percentage of cases the associate has won.

Juniors and interns undertake prescribed training courses and a record is kept. All training courses are registered and the name of the course, the duration (in days), the start date, the end date and details about the training organisation. Although a course is only offered by one training organisation, these organisations typically offer many courses. We store the name, address, telephone, email and Law Society accreditation number for all training organisations. When a lawyer completes a course, the grade received on that course is recorded.

We store details about the qualifications of all lawyers. Each lawyer may have many qualifications and a list of qualifications is stored, including the name of the qualification, its level (undergraduate or postgraduate) and the name of the university offering the qualification.

Each lawyer may take on many cases. A case is assigned to at least one lawyer but may be assigned to as many as four. If more than one lawyer is assigned to the case, one of the lawyers must be designated as a leader. Only seniors may be leaders of cases involving multiple lawyers.  A case must have one or more clients but a client may initiate many cases over time.  For case, we store a unique identification number, the estimated duration of the case, the client number/s of the clients involved, and the estimated start date. For client, we store an identification number, name and address.  When any lawyer is assigned to a case, we store the date assigned and the date the lawyer leaves the case. A lawyer may become involved in a case on multiple occasions.