But he said it's "inconceivable" that someone using a Gmail account would not be aware that the information in their email would be known to Google.
Google has repeatedly described how it targets its advertising based on words that show up in Gmail messages. For example, the company says if someone has received a lot of messages about photography or cameras then it might display an advertisement from a local camera store. Google says the process is fully automated, "and no humans read your email..."
"Users, while they're using their Google Gmail account, have given Google the ability to use the emails they send and receive for providing that service," Somvichian said in court. "They have not assumed the risk that Google will disclose their information and they fully retain the right to delete their emails."
Privacy advocates have long questioned the practice, and were closely watching the lawsuit.
"In this Gmail case Google is trying to argue that its technology is exempt from privacy and wiretap laws. If they win, it will set a horrible precedent that they will try to apply to other Google technologies greatly threatening consumers' privacy rights," Consumer Watchdog Privacy Project director John Simpson said on Thursday.