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 and Customs Enforcement (ICE) got hit with a federal lawsuit on Monday by the American Civil Liberties Union, claiming it failed to respond to open records requests about what it describes as President-elect Donald Trump’s “mass deportation and detention” plans.