## Facts

- Computer Associates International, Inc. (CA) developed CA-SCHEDULER, a job-scheduling program for IBM System/370 mainframes, including an “ADAPTER” component that enabled operation across multiple IBM operating systems.
- Altai, Inc., a competitor, developed the ZEKE job-scheduling program and an interface module called OSCAR to expand ZEKE’s operating-system compatibility.
- Altai hired a former CA programmer familiar with ADAPTER; he used CA source code he had taken to create OSCAR 3.4, which included substantial literal copying from ADAPTER.
- After CA discovered the copying and sued, Altai rewrote the interface module as OSCAR 3.5 using a purported clean-room process designed to avoid reliance on CA’s code.
- CA alleged that OSCAR 3.5, even without literal copying, infringed ADAPTER’s protectable non-literal elements (structure, sequence, and organization) and also asserted a state-law trade secret misappropriation claim.

## Issues

1. What test governs copyright protection and substantial similarity for a computer program’s non-literal elements, and did OSCAR 3.5 infringe ADAPTER under that test?
2. Whether CA’s state-law trade secret misappropriation claim was preempted by Copyright Act § 301.

## Decision

- The Second Circuit affirmed the finding that OSCAR 3.5 did not infringe CA’s copyright.
- The court adopted the abstraction–filtration–comparison (AFC) test to evaluate non-literal infringement of computer programs.
- The court vacated the ruling that CA’s trade secret claim was preempted and remanded for further analysis.
- Altai’s liability and damages for literal copying in OSCAR 3.4 were not contested on appeal.

## Legal Principles

- Copyright protects a computer program’s literal code, but claimed similarities in non-literal elements require separating protectable expression from unprotectable ideas, processes, and constraints.
- The AFC test:
  - Abstracts the program into levels of generality (from code to modules to overall architecture).
  - Filters out unprotectable material at each level, including ideas/processes, elements dictated by efficiency, elements dictated by external factors (hardware, operating systems, compatibility demands, and industry practices), and public-domain material.
  - Compares only the remaining protectable expression to determine substantial similarity.
- Similarities driven by functional requirements, interoperability demands, or standard programming practices are excluded from the infringement comparison.
- Copyright Act § 301 preempts a state claim only if (1) the work falls within copyright subject matter and (2) the state-law rights asserted are equivalent to copyright rights; “extra elements” (such as breach of confidence or improper acquisition) can make a trade secret claim qualitatively different and not preempted.

## Conclusion

The Second Circuit established the abstraction–filtration–comparison framework for assessing non-literal software infringement, affirmed that Altai’s rewritten OSCAR 3.5 was not substantially similar in protectable expression to CA’s ADAPTER, and held that trade secret misappropriation is not automatically preempted, requiring an “extra element” analysis on remand.


Computer Assocs. Int’l, Inc. v. Altai, Inc., 982 F.2d 693 (2d Cir. 1992)