The U.S. Supreme Court has jumped into a titanic copyright battle between Oracle Corp. and Google LLC with both barrels.

The high court granted Friday Google's petition for certiorari—leaving the court free to address the copyrightability of software and the defense of fair use. The court's involvement is sure to reignite a 50-year-old debate over how much, if any, software should be subject to copyright, and the contours of the fair use defense in the digital age.

"This is the copyright case of the century," said Stanford law professor Mark Lemley, who has represented Google in copyright matters but isn't speaking for the company in this case. "However it is decided, it has the potential to reshape not only software copyright law but copyright doctrine more generally."

Google contends that Federal Circuit decisions in 2014 and 2018 threw "a devastating one-two punch at the software industry." Oracle argues that the industry has in fact flourished in the wake of the rulings.

If the court reverses on either copyrightability or fair use, it likely will end Oracle's nine-year quest for billions in unpaid royalties for Google's use of Java in its Android operating system. Oracle will have to win on both questions to get one more shot at a damages trial before U.S. District Judge William Alsup of the Northern District of California.

The Silicon Valley giants have deployed an army of A-list lawyers in the dispute over Java application programming interfaces (APIs) that Google copied into its Android operating system. The Harvard Journal of Law and Technology devoted a special issue to the case and its implications last spring.

The APIs comprise 11,500 lines of declaring code organized into 37 packages. The code provides a shorthand for accessing preexisting libraries of implementing code. Google copied the declaring code so that programmers could use the familiar Java declarations to build their own Android applications. Google wrote its own implementing code.

"We welcome the Supreme Court's decision to review the case and we hope that the Court reaffirms the importance of software interoperability in American competitiveness," Google's senior vice president for global affairs, Kent Walker, said in a written statement. "Developers should be able to create applications across platforms and not be locked into one company's software."

Oracle spokeswoman Deborah Hellinger said the company is confident the Supreme Court will reject Google's effort to avoid responsibility for its copying. "We believe the Court will reject any reasoning that permits copying verbatim vast amounts of software code, used for the same purpose and same way as the original," she said. "That is not 'transformative,' and certainly not fair use."

Oracle's predecessor Sun Microsystems never successfully developed its own smartphone platform using Java, but it licensed Java to others for their mobile devices. Oracle argues Google usurped that business through its unfair copying. Android had generated more than $42 billion in advertising revenue for Google, according to evidence presented at a 2016 trial.

Alsup ruled following the first trial in 2012 that the APIs are not copyrightable, because they represent a command structure, or method of operation, that could not be written any other way. The Federal Circuit disagreed and sent the case back for a second trial on whether Google's copying was a fair use. The court found in part that Google's claims of interoperability were overblown.

Jurors found the use fair in 2016, but the Federal Circuit reversed again, saying that Google's development of a mobile version of the APIs was not transformative, and that the law protects a copyright owner's right to enter a potential new market.

Google argued in its cert petition that the APIs provide essential structure for others to build new computer programs, and should therefore be beyond the reach of copyright. The Supreme Court took up a similar issue in 1996′s Lotus v. Borland, but wound up deadlocking 4-4. Oracle has long argued, and the Federal Circuit agreed, that Google purposely made its Android software platform incompatible with Oracle's, undercutting Google's interoperability argument.

As for fair use, Google argued that the Federal Circuit upended "the longstanding expectation of software developers that they are free to use existing software interfaces to build new computer programs." Oracle argued in its brief-in-opposition that it shouldn't be "required to let a competitor copy its code so that it can co-opt the fan base to create its own best-selling sequel."

Amici curiae ranging from computer scientists to IP law professors to the Electronic Frontier Foundation and Microsoft Corp. had urged the Supreme Court to take the case. The Supreme Court has twice asked for the views of the solicitor general, which recommended each time against taking the case.

Michael Barclay, who co-authored an amicus in support of Google for the Electronic Frontier Foundation, said it makes sense that the justices granted cert on the full petition, because the nature of the copyrighted work is one of the statutory fair use factors. "Both issues are intertwined," he said.

Berkeley Law's Pamela Samuelson said she believed the two most significant amicus briefs were from computer scientists who explained what APIs are and why freedom to reimplement them is so important, and from Microsoft, which stated that the Federal Circuit's fair use decision would be "disastrous" for software innovation. "Of course, I like to think the Berkeley brief identifying six specific circuit splits on issues in the CAFC's 2014 decision played a role as well," she added.

Goldstein & Russell's Thomas Goldstein is counsel of record for Google. He took over after Kannon Shanmugam, counsel of record on Google's cert petition, left Williams & Connolly for Paul, Weiss, Rifkind, Wharton & Garrison. Williams & Connolly remains on the briefs with partner Lisa Blatt heading its list. Also appearing on Google's briefs are attorneys at Keker, Van Nest & Peters; King & Spalding; and Kwun Bhansali Lazarus.

Orrick, Herrington & Sutcliffe's Joshua Rosenkranz signed Oracle's brief in opposition. Also on the brief were Orrick partner Annette Hurst; Kirkland & Ellis partner Dale Cendali; Oracle general counsel Dorian Daley and associate GCs Deborah Miller and Matthew Sarboraria.