Michael Dreeben, deputy solicitor general at the US Department of Justice. Michael Dreeben, deputy solicitor general at the US Department of Justice. Photo by Diego M. Radzinsdhi.

Deputy U.S. Solicitor General Michael Dreeben will detour from special counsel Robert Mueller's legal team next week to argue before the U.S. Supreme Court in high-profile privacy case.

The Justice Department's top expert on criminal law cases will argue in Carpenter v. United States on Nov. 29 that police collection of cellphone data does not constitute a search of defendant Timothy Carpenter, accused of armed robbery of cellphones, and does not violate the Fourth Amendment.

Dreeben was recruited by Mueller in June to assist with the probe into Russian connections with the Trump campaign. The department made it clear from the outset that Dreeben was not working with Mueller fulltime but would continue to tend to the high court's criminal docket when he could.