This study analyzes the 115 U.S. federal cases regarding the copyright protection of computer programs, in order to examine how legal actors with different resources interact through their strategic communication activities, which influence the structuring of the information environment of the copyright system. The framework of "authorship," "work," and "use" helps us understand the stakeholders' relationships and struggles that are manifested in their legal arguments. The structural rules mainly concerning the concept of authorship and work at first enabled the developers and copyright holders to make effective arguments to extend copyright protection on their behalf. When the cases began to have more actors who are developers but not copyright holders and the actors who are not developers but claim their rights in the programs, the struggle between the developers and non-developers were manifested in their arguments focusing on the concept of work and that of authorship. Through the legal actors' constant efforts to legitimize their interests in computer programs, the construct of authorship has been mobilized yet remained central. Artistic creativity that had been emphasized in other areas of copyright, and "independent" creativity that had been emphasized in earlier cases of software copyright, is later transformed to "scientific expertise, knowledge, and skills." The findings of this study demonstrate the importance of the role of communication in structuration, because the only way that the legal actors were able to legitimize their interests and possibly transform the existing structural rules was through their communicative activities. The nature of the actor, i.e., whether she was a developing entity, was found to be a single most important factor that influences the decisions made by the judges. However, only when the legal actor could successfully present herself as a party that involved with developing computer programs, the judges were more likely to make a decision in her favor. When the actor was a developer but she focused her arguments on the nature of the work rather than her developing activity, the actor tended not to have any advantage over the other party. Therefore, it was the legitimacy gained by communicating the nature of the actor, rather than the nature of the actor itself, that made the difference in the ways the judges made decisions.