After 160 years, Supreme Court to settle birthright citizenship for illegal immigrants

You don't have to delve deeply into the U.S. Constitution to see the word "citizen." The word first appears in Article I, Section 2, which states that to serve in the House of Representatives, a person must have been a citizen for seven years.

"Citizen" appears 10 more times in the original seven articles that discuss the qualifications for office, legal disputes and rights.

Yet nowhere does the Constitution define what a citizen is.

In 1866, when Congress was debating the 14th Amendment, guaranteeing citizenship rights to former slaves, Sen. Edgar Cowan made that point: "I am really desirous to have a legal definition of 'citizenship of the United States.' What does it mean? What is its length and breadth?"