Andy Rubin, the head of Google's Android development team, took the witness stand for the first time Monday in Oracle's lawsuit accusing Google of patent and copyright infringement in its Android OS.
Rubin tussled with noted trial lawyer David Boies, acting for Oracle in the case, over emails that Rubin sent or received in 2005 and 2006, when Google was first starting its Android development.
Oracle has accused Google of infringing its Java patents and copyrights in Android. Google denies any wrongdoing, saying it built a "clean room" version of Java that does not contain any of Oracle's protected intellectual property.
Oracle says the emails are evidence that Google knew it needed a license for Java to build Android, but that it forged ahead without one because it failed to negotiate a Java license with Sun. Oracle acquired the rights to Java when it bought Sun two years ago.
In one of the emails, Rubin wrote: "I think a clean room implementation is unlikely because of the team[']s prior knowledge, and it would be uncharacteristically aggressive of us to position ourselves against the industry."
"So you're saying that team had too much prior knowledge to operate in a clean room environment, correct, sir?" Boies asked Rubin.
"I think that's reading a lot into that small sentence," Rubin answered. "I wouldn't go that far."
In another email, Rubin wrote that the Java.lang API (application programming interface) was covered by copyright.
"You meant copyrighted by Sun, yes?" Boies asked.
"I didn't say that," replied Rubin.
"But you meant Sun, yes?" asked Boies.
Rubin: "Yes, in the context of this I think that I meant the APIs were copyrighted."
"By Sun?" Boies pressed.
"Yes," replied Rubin.
The Android chief was questioned for only 25 minutes, since he was called to the stand shortly before the trial ended for the day. Oracle will resume his questioning Tuesday, when Eric Schmidt, Google's executive chairman, is also expected to testify.
Earlier Monday, Oracle called Bob Lee, a former Google engineer who is now the CTO of software vendor Square, and John Mitchell, a computer science professor at Stanford, who is employed by Oracle as an expert witness in the case.