The Supreme Court on Thursday seemed open to lifting a series of nationwide orders blocking President Donald Trump from enforcing his birthright citizenship policy even as several of the justices wrestled with the practical implications of allowing the government to deny citizenship to people born in the US.

The Citizenship Clause, ratified in 1868 after the Civil War, was included to ensure that formerly enslaved people would be citizens. It effectively overturned the notorious Dred Scott decision, in which the Supreme Court held that Black people, no matter their status, were not citizens.

A case focused on birthright citizenship could come later, but the bulk of the argument is expected to concern whether a single judge can freeze a policy nationwide.