Today, a jury in California's Northern District federal court declared that Google's use of copyright-protected code in Android was fair use, freeing it of any liability. Oracle, which controls the copyright on the code, had been seeking $9 billion for the use of the code.

The case centers around an API developed by Java and owned by Oracle, which allows outside programs to easily interact with Java programs. Android uses the same API, and in 2014 a federal appeals court ruled that Oracle has a valid copyright claim on the API code, potentially putting Google on the hook for billions of dollars in damages. (The Supreme Court declined to hear the appeal.) In the latest round, Google argued that Android's reimplementation of the API constituted fair use, which would allow use of the code without invalidating Oracle's copyright. Ultimately, the jury found that case convincing.

The court fight hinged in large part on archived emails sent by Android founder Andy Rubin, who continued to develop the operating system after it was acquired by Google in 2005. In one email, unearthed through the legal discovery process, Rubin seems to criticize another company's decision to build on top of Java's API, which was owned by Sun Microsystems at the time. "Wish them luck," Rubin wrote in the email. "Java.lang.apis are copyrighted. and Sun gets to say who they license the tck to."

Fair use rulings are made on a case-by-case basis so today's ruling doesn't set any legal precedent, but it's by far the most high-profile decision of its kind. Both Google's Go and Apple's Swift are licensed in a way that would close off the possibility of such a suit in the future. Still, the possibility a number of legal scholars have predicted a "chilling effect" for developers if such lawsuits are common and successful.