On Monday, the Supreme Court opted not to review a 2014 ruling on copyright law that held Google's Android operating system infringed copyrights relating to Oracle's Java platform. This is a disaster for the software industry.

Here's the problem: the digital economy depends on gadgets and software being able to communicate seamlessly. Last year's decision by the Federal Circuit Court of Appeals opened the possibility that efforts to make software work together better could trigger copyright liability. The result could be more compatibility problems and less innovation.

Google thought it was on safe legal ground, but an appeals court disagreed

Google modeled its Android smartphone platform on the Java programming language, which was created by a company called Sun Microsytems. Google didn't get Sun's permission to do this, and Oracle (which acquired Sun a few years ago) sued for copyright infringement.

But Google argued that it had acted within the law. It had only copied those characteristics of the Java system necessary to allow Android to run Java software. Google believed that was legal because copyright law doesn't protect functional characteristics, which the law defines as an "idea, procedure, process, system, method of operation, concept, principle, or discovery."

Google's defenders point to a landmark 1995 ruling, in which an appeals court held that the software company Borland had not infringed copyright when it created a spreadsheet program whose menus were organized in the same way as the menus in the more popular spreadsheet Lotus 1-2-3.

The court held that the order of Lotus 1-2-3 menu items was an uncopyrightable "method of operation." And it concluded that giving Lotus exclusive ownership over its menu structure would harm the public:

Under Lotus's theory, if a user uses several different programs, he or she must learn how to perform the same operation in a different way for each program used. For example, if the user wanted the computer to print material, then the user would have to learn not just one method of operating the computer such that it prints, but many different methods. We find this absurd.

Google only copied those characteristics of the Java system necessary to allow Android to run Java software

Google believed that its own copying was directly analogous to what Borland had done. There were thousands of programmers with expertise in writing Java programs. By designing its platform to respond to the same set of programming commands as Oracle's Java system, Google allowed Java programmers to become Android programmers with minimal training — just as Borland's decision to copy Lotus's menu structure avoided unnecessary training for seasoned Lotus 1-2-3 users.

But the Federal Circuit Court of Appeals didn't buy Google's argument. It held that the technical specifications Google had copied — including the names of functions (such as "max" for the maximum function), as well as what type of data these functions accept and return (like the fact that "max" takes two integers and returns an integer) — was eligible for copyright protection.

API copyrights could be a disaster for the software industry

Programmers call this kind of technical specification an application-programming interface, or API. And a brief drafted by the Electronic Frontier Foundation — and signed by some of the nation's leading computer scientists — argues that the lack of copyright protection for APIs has been essential for the development of the digital economy. A second brief by the group Public Knowledge reaches the same conclusion.

That's because software is all about interoperability. The internet's power comes from the fact that billions of computers can all communicate with one another. And that compatibility is made possible in large part because programmers have had the freedom to do what Google and Borland did: build new software based on de facto industry standards that might originally have been developed by incumbent software companies.

One such industry standard is the Unix operating system, which was developed by AT&T in the late 1960s. Unix became an industry standard, and over the years many people have created "Unix-like" operating systems. One of those Unix clones, called Linux, now provides the foundation for everything from Android phones to powerful web servers. Apple's Mac OS X and iOS operating system also make heavy use of Unix standards.

The internet's power comes from the fact that billions of computers can all communicate with one another

If copyright law had prohibited this kind of copying, people might have been forced to develop mutually incompatible operating system standards. Programmers and systems administrators would have had to waste time learning about a variety of different systems. We'd all be worse off as a result.

A similar type of copying can be essential to keeping older devices working, as the EFF brief explains:

Jeremiah Flerchinger is an electrical engineer with over ten years of service in the Department of Defense, after previous experience with a machine-tool company. When the National Aeronautics and Space Administration (NASA) sought to repurpose old manufacturing robots for a new project, they asked Flerchinger’s company to manufacture and program updated memory chips to store the robots’ new instructions. Configuring firmware to put on the chips required using obsolete software that wouldn’t run on modern computers. Flerchinger reimplemented the software’s API, creating modern software that could fulfill the same functions and work alongside old machines that had the same API hard-coded into their electronics.

As software is increasingly incorporated into a wide variety of products — industrial equipment, automobiles, and even children's toys — restricting this kind of reverse-engineering will have huge costs.

Disclosure: My brother is an executive at Google.