Google and Oracle renewed a copyright skirmish over computer code on Wednesday in a long-running dispute that has major implications for the U.S. tech industry.

The case turns on the Android operating system and whether Google GOOG must pay Oracle ORCL for using APIs related to the Java programming language. APIs (application programming interfaces) allow software programs to communicate with each other, and they are integral tools for countless internet applications. A copyright ruling in favor of Oracle could curtail their use.

In the Wednesday hearing, which took place in San Francisco, the companies offered U.S. District Judge William Alsup a preview of the arguments they expect to make before a jury in May.

Google’s argument centers on the concept of “fair use,” which allows the use of a work without the permission of the copyright owner. To determine if the implementation of the Java APIs qualify as fair use, a jury will have to employ a familiar four-part test that includes a consideration of whether a work is “transformative.”

According to Google’s lawyer, Robert Van Nest, the company used only a tiny fraction of the overall code found in a set of 37 Java API packages, and it did so in a novel way.

“The APIs were never intended to be used on a smartphone,” said Van Nest, according to a source in the courtroom. “Google’s limited use did create something completely different.”

Oracle is claiming that the amount of code employed by Google exceeded the boundaries of fair use, and that Google should have to pay millions of dollars based on special penalties set out in copyright law. Oracle declined to comment on the latest proceedings.

The issue is now going before a jury, but not for the first time. In 2012, another jury was unable to decide on the fair use question as part of a larger case that also involved patent law.

In the early proceedings, the copyright question was decided by Judge Alsup, who found that APIs are functional in nature and not covered by copyright at all. His finding, however, was overruled by the U.S. Court of Appeals for the Federal Circuit in a decision that was widely criticized by legal scholars and computer scientists.

After the Supreme Court declined last year to review the copyright issue, the case dropped back to Judge Alsup’s court where a jury will resolve the fair use issue and, if necessary, the amount of damages.