Attaining and maintaining a substantial Jewish majority in Israel has been one of the basic goals of the State of Israel since its early years. A substantial Jewish majority within the borders of the state is thought to be necessary in order to preserve its Jewish nature. Many believe that the demographic consideration also stood behind the enactment of the Citizenship and Entry into Israel Law (Temporary Provision), 2003, which prohibits granting Israeli citizenship and residency to Palestinians from the West Bank and the Gaza Strip, and prevents, inter alia, Israeli Arabs from living in Israel with their Palestinian spouses.I examine the legitimacy of the demographic consideration from the perspective of liberal political theory. I conclude that demography can, in principle, be a legitimate consideration in deciding immigration policy, and its justification can be derived from the liberal justification of the right to national self-determination. However, the demographic consideration must be assigned its proper role and weight relative to other important liberal values such as equality and other human rights. I suggest that the demographic consideration might be legitimate only to the extent that it is not used to justify immigration policies that violate constitutional rights.I then discuss the Supreme Court decision concerning the constitutionality of the Citizenship and Entry into Israel Law. I demonstrate that, contrary to statements by the judges themselves, the demographic consideration played a key role in the opinions of several judges. It was, however, a hidden consideration. It was not openly acknowledged and discussed. Consequently, a careful examination and balancing of the demographic consideration could not take place. The result was that the actual influence of the demographic consideration on the outcome of the case was much stronger than can be reasonably justified according to liberal principles of justice.