"Removable criminal aliens" are non-citizens who have been convicted of committing crimes in the U.S. that warrant immediate deportation hearings. Based on data from 2007 to 2009, the Obama administration Department of Homeland Security estimated in 2010 that "900,000 arrests of aliens for crimes occur every year," "550,000 criminal aliens convicted of crimes exit law enforcement custody every year," and "1.94 million removable criminal aliens are in the United States today." Since that time, hundreds of thousands of removable criminal aliens have been deported, and a unknown number of aliens have committed crimes that warrant immediate deportation hearings.