This quota was attached as a requirement to the 2005 DHS spending bill, basically asking ICE to keep a minimum of 18,500 immigrants detained at all times. That number was raised by Congress to 33,400 in 2009 and 34,000 in 2011.
Created as a response to the 9/11 attacks, DHS assimilated the Imkmigration and Naturalization Service and divided its functions into two agencies: ICE and Citizenship and Immigration Services. Its main goals are protecting the country from terrorist attacks and natural disasters.
The Supreme Court decided on this case that immigrants cannot be held in detention indefinitely. The court ruled that a hearing must be held after a six-month detention and, if the immigrant is not going to be deported, he/she should be let go.
This act substantially changed immigration in the U.S. Among its most important provisions are the creation of the program 287g, the expansion for mandatory detention and the redefinition of aggravated felony for immigration purposes.