Two (count 'em, two) different authorities have so far held that it is per se unethical for a lawyer to provide a non-infringement or invalidity opinion about another client's patent. Va. Op. No. 1774 (Feb. 13, 2003); Andrew Corp. v. Beverly Mfg. Co., 2006 U.S. Dist. LEXIS 6360 (N.D. Ill. Feb. 16, 2006) (non-infringement). Andrew is particularly worrisome (and wrong) because it concludes that an opinion given by a conflicted lawyer is "incompetent" as a matter of law, and therefore inadmissible to defend against a charge of willful infringement.
It seems to me that a per se approach to either of these issues is wrong. On the noninfringement side, let me come at it from the easy way: Client A comes to a lawyer and asks, "I want to make a new pizza, do I infringe any patents if I do so?" and the lawyer says "no" after conducting a clearance search, analyzing the closest patent (held by a non-client) -- even though her firm represents hundreds of clients with thousands of patents. Why is it ethical to give a non-infringement opinion under that circumstance? I think because no reasonable lawyer would contend there was infringement. Put another way, the duty of loyalty that a lawyer owes to a client does not include the duty to make frivolous interpretations of a patent. So, it seems to me that a lawyer should be free to give noninfringement opinions so long as no reasonable lawyer would find there was infringement.
Now, real world: that won't help much because the only time an opinion is likely to be needed is when there's a reasonable argument about it. But the rule needs to be right, because I guarantee this issue will pop up in ways that no one has ever thought of... yet.
Invalidity presents a closer, more difficult question. My initial thoughts are that an invalidity opinion will often constitute an adverse representation, but I would love to hear more thoughts about that.
More to come...