President Trump's executive order challenging birthright citizenship will face its first legal test in a Seattle courtroom Thursday.

President Donald Trump is seeking to end birthright citizenship, a move to cut off a longstanding constitutional right that could leave hundreds of thousands of Texas children without legal status. The move has been questioned by legal scholars and it has already drawn lawsuits from the American Civil Liberties Union and a coalition of Democratic-led states.

One of the many executive orders President Donald Trump signed on Monday included one to end birthright citizenship. Here's what to know about it and why lawsuits have already been filed.