Airframe Sys., Inc. v. L-3 Commc’n Corp.
In 1979, plaintiff began developing proprietary aircraft maintenance tracking software; it has continually modified the source code for the software. Source code is the original version of a computer program that is written in human-readable words and symbols and must be compiled into machine-readable object code before a computer can read and execute the software. A program in source code format can be modified by a programmer, whereas a program in object code format cannot be easily modified. Plaintiff began licensing the software to defendant in 1986, limited to use in object code format, and registered four versions of the source code with the U.S. Copyright Office in 2003. After discovering unlicensed versions on defendant's computers, plaintiff brought an infringement action. The district court entered summary judgment for defendant. The First Circuit affirmed. Plaintiff, by comparing what was found on defendant's computers to the 2009 version of its source code, did not produce sufficient evidence of "substantial similarity" between the copyrighted material and the allegedly infringing material.