One issue I get asked about a lot is what are the pros and cons of litigating a patent you/your firm prosecuted. There are obvious benefits: expertise and efficiency being the obvious two. There are obvious downsides. Perhaps the most glaring one occurs when the defendant accuses the attorney of having committed inequitable conduct. (There are lots of pros and cons; those are a couple.)
I hadn’t thought of this one, or don’t think I have, but add it to the con list: the continuous representation doctrine. Under this doctrine, the statute of limitations on a legal malpractice claim is tolled while the firm continues to represent the client. Depending on state law, this can mean that, even if the client discovered the harm, limitations is tolled.
So, if you prosecute a case, and then litigate it, you may be extending limitations on any error that occurred during prosecution. (You also, by the way, have a duty to disclose any error you learn about to your client.) For a recent case applying this doctrine and resulting in a $17m judgment being upheld against a firm (though not in the patent context), see Red Zone LLC v. Cadwalader, Wickersham & Taft, LLP (N.Y.App. Div. June 19, 2014).