...He argued that disclosure of the search warrant would preclude the government from monitoring the account, should such a step become necessary in the investigation. Machen added that “some investigations are continued for many years because, while the evidence is not yet sufficient to bring charges, it is sufficient to have identified criminal subjects and/or criminal activity serious enough to justify continuation of the investigation.”Machen insisted the investigation would be compromised if Rosen was informed of the warrant, and also asked the court to order Google not to notify Rosen that the company had handed over Rosen’s e-mails to the government.
I see that Machen has a connection to the contempt of congress thing on Holder: