[Excerpt] Immigration is a discretionary policy of every nation state. No citizen of any foreign nation has a right to enter any other country for the purpose of permanent settlement or for employment just because he or she wishes to do so. The opportunities and the conditions under which they may enter are legally prescribed. Hence, in the contemporary case of the United States, it is the nation's immigration policy that is the source of the conflict with the national interest, not the actions of those who, as individuals, are merely availing themselves of its terms and opportunities.