[TBP]

http://therightscoop.com/mark-levin-congress-can-end-birthright-citizenship-without-amending-the-constitution/

These classes of people, even if born here, are NOT American citizens under the Immigration and Naturalization Act of 1952:

a child born on American soil to a:

(1) foreign ambassador,
(2) head of state,
(3) foreign military prisoner

So what prevents Congress from simply adding another class of people to the list?

[BuckeyeTexan]

These classes of people, even if born here, are NOT American citizens under the Immigration and Naturalization Act of 1952:

a child born on American soil to a:

(1) foreign ambassador, (2) head of state, (3) foreign military prisoner

So what prevents Congress from simply adding another class of people to the list?

Nothing, so long as those in the new class don't have citizenship guaranteed by the U.S. Constitution.

[RIghtwardHo]

Because there is a constitutional Amendment that prohibits it. The option is an a Constitutional Amendment.