In concluding that the claim term "an encrypted digital information transmission including encrypted information" in U.S. Patent No. 8,191,091 is limited to all digital signals contrary to the Patent Trial and Appeal Board's interpretation, the Federal Circuit stated that:
"Even where “prosecution history statements do not rise to the level of unmistakable disavowal, they do inform the claim construction.” "[T]he Board erred by effectively requiring the prosecution history evidence to rise to the level of a disclaimer in order to inform the meaning of the disputed claim term. Assuming without deciding that PMC’s statements and amendments were inadequate to give rise to a disclaimer, we still find that the prosecution history provides persuasive evidence that informs the meaning of the disputed claim phrase and addresses an ambiguity otherwise left unresolved by the claims and specification."
The Federal Circuit thus vacated the Board's anticipation and obviousness determinations and affirmed the remainder of its determinations.
Read the case here.