This bill amends the Immigration and Nationality Act to mandate the detention of certain inadmissible aliens who are charged with, arrested for, or admit to assaulting a law enforcement officer. The legislation specifies that such an assault qualifies if it occurred while the officer was performing official duties, because of those duties, or due to their status as an officer. For the purposes of this act, a "law enforcement officer" is broadly defined to include individuals involved in law enforcement activities, as well as firefighters and other first responders . The bill further requires the Secretary of Homeland Security to issue a detainer for these aliens and expeditiously take custody of them if they are not already detained by other authorities.