Enforcement of the law will allow people to learn in advance whether a mobile app will collect personal data and give them a chance to refuse to download it.
California Attorney General Kamala Harris announced in San Francisco that she has determined that a state online privacy law covers the hundreds of thousands of mobile applications used by Californians and that she is taking steps to enforce it.
Harris said she has reached an agreement with six leading Internet platform operators, including Google, Apple and Microsoft, on principles for making mobile app developers aware of the law and requiring them to observe it.
If the app developers don't obey the law, Harris said, "We can sue and we will sue."
"We have forged an agreement to strengthen privacy protection for millions of mobile app users in California and around the world," Harris said at a news conference at the State Building.
Mobile apps, used on devices such as smartphones and computer tablets, are connections to websites designed for specific tasks, which could range from finding the next bus to creating an online journal.
The policy must explain what information the app collects and what entities are given the information.
The law doesn't prohibit developers seizing personal information, such as a contact list or identifying data, from the devices of consumers who download their apps. That practice by some developers, often carried out without consumers' knowledge, has been the subject of recent news reports.
But Harris said enforcement of the law will help consumers by enabling them to learn in advance whether a mobile app will collect personal data and giving them a chance to refuse to download it.
"The consumer has the right to know this information and to have the tools to have control," she said.
She said that until now, there has been some confusion about whether the privacy law applies to mobile apps, but her staff has now resolved that issue by determining that it does.
Violations of the law could result in fines of $5,000 per user, she said.
In addition to Google, Apple and Microsoft, the platform operators that signed on to the agreement are Amazon, Hewlett-Packard and Research in Motion, the maker of the Blackberry smartphone.
Harris said the Apple App Store sells nearly 600,000 mobile apps and Google Android Market sells another 400,000. These apps have been downloaded more than 35 billion times, she said.
Although it applies only to apps used by California residents, the state's plan is expected to have national and possibly international impact because of the number of Californians and because it would be complicated for developers to work out a way to display their privacy policies only to Californians.
Harris said she and her staff has been working with the platform companies to develop the agreement since August.
Mitchell Kapor, a San Francisco technology expert and founder of Lotus Development Corp. who has been an advisor to Harris, said he thinks the agreement is a good first step.
"A big impact of having this agreement is that there is much more clarity on what's fair territory and what's foul territory for app developers," he said.
"They will now pay attention to this issue and it means there are very many privacy infractions that will never take place," Kapor said.
He called the state's plan "a significant series of steps on a long and ongoing journey" to consumer privacy and to "how we will live with all this technology and how it changes our world."