Federal Material Witness Statute: A Legal Overview of 18 U.S.C. 3144 [July 1, 2011] [open pdf - 971KB]
From the Summary: "This is an overview of the law under the federal material witness statute which authorizes the arrest of material witnesses, permits their release under essentially the same bail laws that apply to federal criminal defendants, but favors their release after their depositions have been taken. Legislative efforts in the 109th Congress to amend the provisions never fully developed. Witnesses at Congressional oversight hearings did alleged that the authority to arrest and hold material witnesses until their appearance at federal criminal proceedings (including grand jury proceedings) had been abused following September 11, 2001. Section 12 of the USA PATRIOT Act and Terrorism Prevention Reauthorization Act (H.R. 3199) as reported by the House Judiciary Committee would have required periodic reviews and reports on the use of the material witness statute. In the face of Administration opposition, however, the provision was dropped from the bill prior to House consideration."
CRS Report for Congress, R41903
Congressional Research Service: https://crsreports.congress.gov/