The Supreme Court on Monday asked the Obama administration for its views on an appeals court's conclusion that Oracle's Java application programming interfaces are protected by copyright.

The move (PDF) by the justices indicates that the high court is interested in the hotly contested intellectual property dispute. But whether the Supreme Court will enter the legal thicket won't be announced until after the administration responds in the coming months.

The legal fracas started when Google copied certain elements—names, declaration, and header lines—of the Java APIs in Android, and Oracle sued. A San Francisco federal judge largely sided with Google in 2012, saying that the code in question could not be copyrighted.

A federal appeals court reversed that decision in May.

"Because we conclude that the declaring code and the structure, sequence, and organization of the API packages are entitled to copyright protection, we reverse the district court’s copyrightability determination with instructions to reinstate the jury’s infringement finding as to the 37 Java packages," the US Appeals Court for the Federal Circuit had ruled.

Google appealed to the Supreme Court. Several friend-of-the-court briefs submitted to the high court backed the search giant, including a submission from computer scientists like Vinton "Vint" Cerf—the father of the Internet—and Python creator Guido van Rossum. They said that assigning copyright to the code, or API, that enables programs to talk to one another sets a dangerous precedent.

The Federal Circuit’s decision poses a significant threat to the technology sector and to the public. If it is allowed to stand, Oracle and others will have an unprecedented and dangerous power over the future of innovation. API creators would have veto rights over any developer who wants to create a compatible program—regardless of whether she copies any literal code from the original API implementation. That, in turn, would upset the settled business practices that have enabled the American computer industry to flourish, and choke off many of the system’s benefits to consumers. [PDF]

The scientists described APIs as "specifications that allow programs to communicate with each other. So when you type a letter in a word processor and hit the print command, you are using an API that lets the word processor talk to the printer driver, even though they were written by different people."

Oracle, which is seeking as much as $1 billion in damages, said the appellate court's decision was a "win for the entire software industry that relies on copyright protection to fuel innovation." The company said that "Google was free to write its own code" but instead "plagiarized."

In his 2012 ruling in Google's favor, US District Judge William Alsup wrote that even though Google could have rearranged "the various methods under different groupings among the various classes and packages," the overall name tree is "a utilitarian and functional set of symbols, each to carry out a pre-assigned function... Duplication of the command structure is necessary for interoperability."

The judge compared APIs to a library, with each package as a bookshelf, each class a book on the shelf, and each method a chapter out of a how-to book.

"As to the 37 packages, the Java and Android libraries are organized in the same basic way but all of the chapters in Android have been written with implementations different from Java but solving the same problems and providing the same functions." The declarations, or headers, "must be identical to carry out the given function," Alsup wrote.

About 97 percent of the source code in the API packages is different. It's only the three percent that overlaps that formed the heart of Oracle's copyright claim. That three percent included packages, methods, and class names and is no longer in Android.

The appellate court's ruling (PDF) left open the door that Google may not be monetarily liable for infringement. The appeals court sent the case back to the lower courts to determine whether Google had a "fair use" right to infringe.

However, there's no clear answer as to what constitutes fair use, as it is decided on a case-by-case basis.

"The distinction between what is fair use and what is infringement in a particular case will not always be clear or easily defined. There is no specific number of words, lines, or notes that may safely be taken without permission. Acknowledging the source of the copyrighted material does not substitute for obtaining permission," the US Copyright Office says.

For the moment, the litigation is on hold, pending the Supreme Court's decision.