Apple has been accused of "dishonest and deceptive business practices" by offering the iOS 4 update to iPhone 3G despite knowing it would affect the performance of the smartphone.
The lawsuit, which was filed last week in California, alleges that the update rendered the device virtually useless.
The company has also been accused of misleading iPhone 3G users by claiming that the OS update was a "significant advance and triumph" for the device.
The lawsuit has been filed on behalf of Bianca Wofford by law firm Cohelan Khoury & Singer. The suit is seeking, but is yet to receive class-action status.
Wofford alleges in the lawsuit that Apple deliberately waited for three months before releasing an update that would fix the iPhone 3G's problems, despite knowing that thousands of users were affected by it.
The plaintiff has also accused Apple of not allowing users to downgrade from iOS 4 to iOS 3.x, forcing people to purchase an iPhone 3GS or iPhone 4 as a replacement.