Apple is challenging a U.K. Government data access order in the Investigatory Powers Tribunal (IPT), the Financial Times reports. The order targeted iCloud backups that are protected by end-to-end encryption.

Last month, press leaks revealed the existence of the January order asking Apple to build a backdoor in iCloud’s encrypted backups. U.K. officials are exercising powers they hold via national security surveillance legislation to try to force the iPhone maker to provide data in the clear to law enforcement.

Apple responded by announcing it would end U.K. users’ access to the strongly encrypted version of the iCloud storage feature. The challenge via the IPT was filed at the same time, per the FT, indicating that the company is going on the offensive to try to overturn the order against its Advanced Data Protection (ADP) feature, as well as pulling the security offering out of the U.K. market.

A key element is that Apple is continuing to offer the strongly encrypted iCloud backups in other markets — even though the order reportedly sought access to the data of users outside the U.K. market, too. The British Government believes Apple has therefore failed to comply despite shuttering the feature locally, according to the FT.

It also reports that this could be the first time the U.K.’s encryption breaking powers have been tested before the body that oversees the security services, although it suggests the hearing is likely to be held in secret.

Apple declined to issue a new statement on the development, but a spokesperson pointed back to remarks it issued last month. At the time, the company said it was “gravely disappointed” that U.K. users would no longer have access to the security feature.