In an opinion last Thursday, Judge Andrews struck a defendants' prior art arguments as to two references, after it offered them for the first time in an opening expert report served nearly two years after final infringement contentions.
The Court found that the prior art arguments were intentionally withheld, because the defendant used the same expert as other parties in another case on the same patents, and those parties had asserted invalidity based on the relevant references (through the expert) nine months or more before the expert did so here:
[T]here is no explanation why Defendant did nothing to alert Plaintiff of its new theories in the nine months or more before the expert …