Related story on the NYT: The indictment of Rajat K Gupta on conspiracy and securities fraud charges presents the Justice Department with new challenges it has not faced in prosecuting other cases involving insider trading by the hedge fund manager Raj Rajaratnam.

Wiretaps of Mr Rajaratnam played a key role in his own conviction, but whether they will be admissible in court against Mr Gupta, a former Goldman Sachs director, will be a key point that could tip the balance of the case. Read