Three US states and France are considering action against Google over the company's interception of private Wi-Fi data by its Street View vehicles as they collected images in 30 countries.
France and the US states of Connecticut, Illinois and Massachusetts have joined Germany, New Zealand and Australia in launching investigations.
The three US states have sent letters to Google demanding more information about how the data was collected and used since 2007.
Co-ordinated legal action by multiple US states has a better chance of forcing big changes because they can assign more specialists to the case, according to the Financial Times.
In the 1990s, co-ordinated lawsuits between states against the big tobacco companies secured advertising reforms and about $200bn (£134.5bn) in damages.
Google claims the data was collected unintentionally because experimental code was included by mistake in software used by the Street View vehicles.
The company, which is answering inquiries from around the world, said it is working with the relevant authorities to answer their questions and concerns.
Google also maintains that its actions did not break any US law, but Privacy International says intentional interception of data violates laws in at least half the countries concerned.
The organisation said last week that it is planning to file a criminal complaint with the UK police after Google published a third-party audit that alleges the interception of Wi-Fi data was deliberate.
Google has gone about gathering this data in the wrong way because it did not take the privacy element seriously enough, said Simon Davies, director of Privacy International.
Any plan to gather, store and use personal information is bound to run into problems, he said, if it is not done openly and transparently, and does not have a clear benefit to those involved.