The American Civil Liberties Union has filed a lawsuit seeking details from the federal Immigration and Customs Enforcement agency into how it may execute a large deportation program.

The American Civil Liberties Union has launched a lawsuit seeking information about the country’s airline used for deportation flights — information it says will be key for pricing together a “road map” for how the incoming Trump administration will carry out promised mass deportations.

Immigration advocacy group says efforts to deport noncitizens could top $319 billion and have devastating effects on the economy.