In Knorr-Bremse Systeme Fuer Nutzfahrzeuge GMBH v. Dana Corporation, et al. (Fed. Cir. September 13, 2004) the Federal Circuit clearly stated that
We now hold that no adverse inference that an opinion of counsel was or would have been unfavorable flows from an alleged infringer's failure to obtain or produce an exculpatory opinion of counsel. Precedent to the contrary is overruled. We therefore vacate the judgment of willful infringement and remand for re-determination, on consideration of the totality of the circumstances but without the evidentiary contribution or presumptive weight of an adverse inference that any opinion of counsel was or would have been unfavorable. . . .
We answer the four questions presented for en banc review, as follows:
When the attorney-client privilege and/or work-product privilege is invoked by a defendant in an infringement suit, is it appropriate for the trier of fact to draw an adverse inference with respect to willful infringement?
The answer is "no." Although the duty to respect the law is undiminished, no adverse inference shall arise from invocation of the attorney-client and/or work product privilege. . . . A defendant may of course choose to waive the privilege and produce the advice of counsel. However, the assertion of attorney-client and/or work-product privilege and the withholding of the advice of counsel shall no longer entail an adverse inference as to the nature of the advice.
When the defendant had not obtained legal advice, is it appropriate to draw an adverse inference with respect to willful infringement?
The answer, again, is "no." The issue here is not of privilege, but whether there is a legal duty upon a potential infringer to consult with counsel, such that failure to do so will provide an inference or evidentiary presumption that such opinion would have been negative. . . .. Although there continues to be "an affirmative duty of due care to avoid infringement of the known patent rights of others," L.A. Gear Inc. v. Thom McAn Shoe Co., 988 F.2d 1117, 1127 (Fed. Cir. 1993), the failure to obtain an exculpatory opinion of counsel shall no longer provide an adverse inference or evidentiary presumption that such an opinion would have been unfavorable.
Should the existence of a substantial defense to infringement be sufficient to defeat liability for willful infringement even if no legal advice has been secured?
The answer is "no." Precedent includes this factor with others to be considered among the totality of circumstances, stressing the "theme of whether a prudent person would have sound reason to believe that the patent was not infringed or was invalid or unenforceable, and would be so held if litigated," SRI Int'l, Inc. v. Advanced Tech. Labs. Inc., 127 F.3d 1462, 1465 (Fed. Cir. 1997). However, precedent also authorizes the trier of fact to accord each factor the weight warranted by its strength in the particular case. We deem this approach preferable to abstracting any factor for per se treatment, for this greater flexibility enables the trier of fact to fit the decision to all of the circumstances. We thus decline to adopt a per se rule. . . .