How Limitations on Copyright in Computer Programs Are Critical to Software Innovation and Investment. This case raises critical questions about how far copyright extends into the basic communication tools -- Application Programming Interfaces (APIs) -- that are presently ubiquitous in the Web environment and software development generally. APIs establish basic interoperability between systems, between applications and systems, and between applications themselves. This kind of interoperability between programs and systems is foundational to software innovation, as well as to computer systems and ecosystems themselves. Because of this, how copyright's default rules affect interoperability is central to how innovation happens on the ground. These rules have been stable for many years. Baker v. Selden, which was decided in 1879, established that copyright law extends only to creative expression and not to ideas; section 102(b) of the 1976 Copyright Act makes clear that copyright does not cover methods of operation, procedures, processes, or systems; and courts, especially in the Ninth Circuit, have explained how these concepts apply directly to interoperability needs. In the case, Oracle is arguing that high-level aspects of the Java APIs are copyrightable, and so that Google has infringed its copyrights in the Java APIs by using some of them to create a Java implementation for Android. The district court ruled that the elements of the Java APIs at issue are not copyrightable, and that Google had therefore not infringed. The Federal Circuit is now reviewing the case on appeal. In this amicus brief, a wide range of start-up companies, their investors, and innovators, including those who were involved in the similar Lotus v. Borland case thirty years ago, ask the court to consider the impact changing copyright boundaries would have on innovation and investment. It explains how innovators rely on APIs, and how limitations on copyright undergird innovation and competition in the software and Internet spaces. The brief argues that the district court's ruling was correct, and urges the court to preserve the longstanding limitations on copyright in computer programs. It explains that doing otherwise harm what is presently a vital and robust industry, chilling both innovation and the investment that supports it.