A US appeals court has upheld a judgment worth US$440 million (A$612 million) that was won by intellectual property licensing firm VirnetX against Apple in a patent infringement case.
The US Court of Appeals for the Federal Circuit denied Apple's appeal of a 2016 jury verdict originally valued at $302 million that grew to $440 million with interest, enhanced damages, and other costs.
The same patent claims have been ruled invalid by an administrative court, but VirnetX is in the process of appealing those determinations.
Apple said in a statement that it was disappointed in the ruling and planned to appeal.
VirnetX did not immediately respond to a request for comment.
VirnetX, which was founded by employees at government contractor Science Applications International Corporation, holds patents related to secure networks, known as virtual private networks, and secure communications links.
VirnetX and Apple have been fighting over patents since 2010 in rollercoaster litigation that has triggered wild swings in the technology licensing company's stock price.
Reporting by Jan Wolfe. Editing by Paul Simao and Tom Brown