## Facts

- Computer-software company I.C.M. Kabushiki Kaisha (I.C.M.) and computer-hardware company A.G. Soft Kabushiki Kaisha (A.G. Soft) jointly held copyrights in 81 “install batch files” (IBFs).
- The IBFs were used on personal computers running Microsoft’s MS-DOS operating system.
- The IBFs provided instructions to a MENU.EXE file and were used to install basic application programs.
- City Soft Kabushiki Kaisha (City Soft) created and distributed programs that were functionally the same as the plaintiffs’ programs.
- I.C.M. and A.G. Soft asserted that City Soft infringed copyrights in 42 IBFs (a subset of the 81 jointly owned IBFs).
- The dispute focused on whether similarities between the parties’ IBFs reflected copying of protected expression, or instead reflected MS-DOS constraints and commonly used installation command patterns.

## Issues

1. Whether MS-DOS install batch files (IBFs) that provide installation instructions to MENU.EXE qualify as copyright-protected “program works” (or otherwise protected works) under Japanese copyright law.
2. Whether City Soft’s corresponding files copied protectable elements of the plaintiffs’ 42 asserted IBFs, as opposed to elements dictated by MS-DOS operation or standard installation practice.
3. Whether the plaintiffs showed a sufficient prima facie right and need for preservation to justify relief in a (Yo) provisional-disposition proceeding.

## Decision

- The Tokyo District Court treated the IBFs as potentially copyright-protected program expression, while recognizing that protection does not extend to ideas, procedures, or elements determined by functional requirements.
- The court compared the plaintiffs’ asserted 42 IBFs with City Soft’s corresponding materials and focused on whether the matching portions went beyond standard MS-DOS command usage and reflected the plaintiffs’ creative choices in selection and ordering.
- On that basis, the court concluded that infringement was shown at least as to the portions (and files) where City Soft’s similarity could not be explained solely by technical necessity, and it limited any relief to those copied expressive parts rather than to the general installation function.

## Legal Principles

- Software-related materials, including script-like batch files, can be protected by copyright when they are expressed in a creative manner, even if they serve a utilitarian purpose.
- Copyright does not protect functions, methods, procedures, formats, or other elements that are required by an operating system or that are so standard that they leave no room for meaningful author choice.
- Where a work operates under strong technical constraints, the protected scope may be narrow; infringement analysis must separate (i) necessary or standard command content from (ii) the author’s choices in selection, arrangement, and other expressive details.
- In provisional-disposition practice, a claimant must show a prima facie right to be preserved and a need for preservation; when protectability and copying are only shown for limited portions, any remedy should be similarly limited.

## Conclusion

This decision is an early Tokyo District Court treatment of copyright in MS-DOS install batch files: it recognized that IBFs can be protected as program expression, but it confined protection to creative, non-required aspects and evaluated infringement by asking whether City Soft’s similarities reflected copying of those expressive choices rather than mere functional necessity.


Tokyo Chihosaibansho Minji Dai 29-Bu [Tokyo District Court, 29th Civil Division], February 27, 1991, Heisei 1 (Yo) no. 2577 (1991)