Without former U.S. District Judge Richard Holwell, there probably would not have been any prosecution of Rajat Gupta, the former Goldman Sachs director and McKinsey chief convicted Friday of insider trading and conspiracy. In 2010, Holwell ruled that prosecutors could use wiretap evidence in their case against Galleon Group hedge fund founder Raj Rajaratnam, rejecting defense arguments that the government is not authorized to use wiretaps to investigate insider trading. If prosecutors hadn’t been able to use those Rajaratnam wiretaps – in which Rajaratnam obliquely referred to tips from a Goldman insider – it’s unlikely the government would have gone to trial against Gupta, since the tapes were the only link between Gupta’s alleged tips and Rajaratnam’s trades.