An accusation of screwing up a patent application is one thing. But allegedly not telling the client about the gaffe? An electronic billboard maker suing a Morgan, Lewis & Bockius patent lawyer for malpractice says that’s on a whole different level.

Landmark Screens — whose picture-changing billboard can be seen on Highway 101 near San Carlos, Calif. — filed a malpractice suit against Morgan Lewis and San Francisco partner Thomas Kohler in federal court last week. Landmark accuses Kohler of messing up a patent application for the billboard and then of not telling the client about it quickly enough. Damages could be in the millions, said Clark Stone, a MacPherson Kwok Chen & Heid lawyer representing the plaintiff. The Technology Law360 Web site first reported the suit Tuesday.