On both sides of the Atlantic, "citizenship" is the subject of vital and often contentious policy debates. In the United States, a nation famously founded on a creed rather than blood ties, the question of what it means to be an American citizen has always been central to the country's...

On both sides of the Atlantic, “citizenship” is the subject of vital and often contentious policy debates. In the United States, a nation famously founded on a creed rather than blood ties, the question of what it means to be an American citizen has always been central to the country’s...