TYLER, Texas (CN) - A federal judge chided a tech-patent company for trying to change its position as its infringement claims against Texas Instruments head to trial.
U.S. Ethernet Innovations LLC sued Texas Instruments Inc. in 2011 for infringing on three patents that "claim methods and apparatuses intended to increase the efficacy of Ethernet communication," according to the ruling.
One point of contention in the litigation has been a claim in the '874 patent involving the "selective masking" of interrupt signals as they pass through a mask or memory.
Schneider explained that "the parties disputed whether selective masking requires the interrupt signal to have the same number of bits before passing through a mask or memory as the number of bits it has after passing through the mask or memory."
The plaintiff defended its claims at summary judgment by taking the position that "the '874 patent does not require a one-to-one correspondence between the number of bits in and the number of bits out," according to the ruling.
At the April validity trial, however, an expert for U.S. Ethernet specifically distinguished prior-art references on the basis that the prior art lacked a one-to-one correspondence.
U.S. District Judge Michael Schneider noted that this position "contradict[ed] its earlier summary judgment briefing."
It persuaded the jury, however, which returned a verdict finding the '874 patent to be not invalid.
Granting TI's request for judicial estoppel, Schneider forbade the plaintiff from relying "on a contradictory argument in the infringement phase."
"The court finds that plaintiff would derive an unfair advantage if it is allowed to argue contradictory positions to the two juries," according to the ruling.