Apple is now asked by the Justice Department to unlock nine iPhone apart from the iPhone used by one of the attackers of San Bernardino.
The iDevice giant said abiding by the demand could post a threat to encryption safeguards that is not limited to the single California case.
Apple lawyer Marc J. Zwillinger said the company is fighting the demands in at least seven of the nine cases and until now has not agreed to perform any government defined services on the devices.
A letter given by the lawyer and unsealed in federal court reads the company has objected the efforts of Justice Department to force cooperation through a 1789 statute called All Writs Act.
The act reads court can require actions to comply with orders.
The Justice Department is looking for technology assistance from Apple in the process of unlocking the iPhones. After several failed attempts access to the iDevices are permanently blocked. FBI wants to grant unlimited attempt.
According to Apple’s chief executive Timothy D. Cook, if the company creates such technology once, it could be used repeatedly on any number of devices.
Apple said the law enforcement possess hundreds of iPhones and they would in future look for similar assistance from them if FBI wins the case.