You lost me on that one. How can you own a patent that is essential and not be valid? If it is essential then if you manufacture you infringe, as essential isn't circumvented. What would they be arguing if it wasn't the patent itself, and what could the judge declare as essential if it wasn't the patent?
This is the way I understand things, but as always with courts my view could be wrong.
Market Data 
Markets 
AI
