Apple has filed a suit against Nokia alleging patent infringement.
The filing claims that the Finnish phone giant infringed on some 13 of its own patents regarding handset operation and connections with computers.
"Other companies must compete with us by inventing their own technologies, not just by stealing ours," said Apple general counsel and senior vice president Bruce Sewell.
Apple's suit was filed in response to a patent motion filed by Nokia in October.
That suit alleges that Apple had been using its patented systems without obtaining a license.
At the time, Nokia said that Apple was trying to get a "free ride" on its research efforts.
The filing is the latest bit of legal drama to involve what has been an otherwise widely successful year for Apple's mobile phone venture.