Documents obtained by the ACLU reveal that in 2011, the Justice Department obtained 37,616 court orders for pen registers and trap and trace devices and 1,661 orders targeting individuals’ e-mail and network data, representing an increase of 64% since 2009.
See the ACLU blog on this increase in warrantless surveillance here: http://www.aclu.org/blog/national-security-technology-and-liberty/new-justice-department-documents-show-huge-increase