Based on posts, I'm getting the sense that Amphastar is saying, yes we used the patented technology but only once or twice... and maybe before the patent was actually granted. It's analogous to a manufacturer saying, "yes I use a patented piece of equipment in my process, but I haven't touched it lately, so I'm OK."
Amph is relying on the Bolar amendment which allows a company to use a patented process in the ANDA to get approval. When the patent expires they can sell their stuff. MNTA's claim is a little different in that their process will continue to have a patent. Any use of a patented device or process to make money is infringement if that process continues to have a valid patent.
From DD on Ihub:"...the Judge will surely continue the TRO long enough for him to decide what he wants to do in response to today’s hearing. Moreover, if the Judge ends up deciding not to continue the TRO or grant a PI, MNTA will almost certainly ask for a stay of the Judge’s decision pending an emergency appeal."