State Senator Alan Lowenthal, a Long Beach Democrat, and Consumer Watchdog, a privacy group that supports the bill, in a press conference Monday. Lowenthal originally introduced a placeholder bill in February, then amended the bill March 24 to include new do-not-track language.

"Nearly 80 percent of Californians use the Internet and nearly 45 percent use Facebook -- including myself," Lowenthal said in a statement. "But today millions of Californians are unaware that their online behavior is being tracked; their data collected and sold to advertisers."

Lowenthal's legislation, designated as a computer spyware bill, would direct the California attorney general to adopt regulations requiring Web companies that collect personal data to allow users to opt out of data collection and online tracking.

The regulations would also require Web companies doing business in California to inform users of their collection and tracking efforts, and it would allow civil lawsuits against companies that fail to comply with the regulations.

The bill would hurt the Internet, said Steve DelBianco, executive director of NetChoice, an e-commerce trade group.