"[T]his report surveys the various authorities governing immigration detainers, including the standard detainer form (Form I-247) sent by ICE to other law enforcement agencies. The report also discusses key legal issues raised by immigration detainers, including (1) whether DHS’s detainer regulations and practices are beyond its statutory authority; (2) whether states and localities are required to comply with immigration detainers; (3) who has custody of aliens subject to detainers; and (4) whether detainer practices violate aliens’ constitutional rights. In considering these topics, it is important to note that Form I-247 and DHS’s detainer practices have changed several times since 2010,15 and that decisions on the merits have not yet been issued in many cases challenging the use of detainers in conjunction with the Secure Communities program. This program arguably raises more issues regarding ICE’s use of detainers than were raised by earlier programs and practices because it takes a broader approach to identifying aliens who may be subject to removal." - Kate M. Manuel, April 24, 2014.