Copyright works can often be the result of input from more than one person. The work will be considered one work (work of joint authorship) if the work has been produced by the collaboration of the authors and the contribution of each is not separate from the contribution of the others. Otherwise there will be two or more works with separate authors.
This is important in many commercial settings where a variety of authors contribute to a work, which may be the main commercial product of the organisation. This occurred in Career Step, LLC v TalentMed Pty Ltd (No 2)  FCA 132. Career Step, a US company, produced on-line materials for a course for training medical transcriptionists. It licensed the course to TalentMed for use in Australia. TalentMed decided to produce its own course which copied parts of the Career Step course materials.
The Career Step’s course materials had 23 modules, some authored by one person but most authored by several. While many authors contributed to multiple modules, the combination of authors was not the same for all modules. The question was – were the course materials a single work or 23 works?
Crucially, the judge held that it was not necessary for each of the authors to contribute to each of the modules. Rather, they had a common purpose (to produce the course materials) and the whole 23 modules were a work of joint authorship in which copyright subsists.
This is significant because, even though the work of some authors related to some modules but not others, ‘collaboration’ can be established by having common purpose. This is likely to assist companies in establishing copyright in works that involve the contributions of many of their staff.