Though the Court recognized Congresss inherent and inalienable right to exclude or to expel all aliens,244 it flatly rejected the idea that this, or any other, power could be used to restrict the effect of birth, or otherwise abridge the rights conferred by the Constitution.245 The Court reaffirmed this principle in Afroyim v. Rusk, noting that Congress c[an]not do anything to abridge or affect . . . citizenship conferred by the Fourteenth Amendment.246 Thus, even if Congress can restrict an alien entrants legal capacity to establish U.S. domicile for state law purposes (as was the issue in Elkins),247 it cannot do so for purposes of the Citizenship Clause. To allow otherwise would effectively give Congress authority to deny birthright citizenship to any person born of alien parents. Such a result not only conflicts with the Courts opinion in Wong Kim Ark, it goes against the very purpose of having a constitutional rule of birthright citizenship in the first place, namely, to put the issue beyond the legislative power.
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It is important that the context for the above quotation be clear. The author concludes that "subject to the jurisdiction" is really a synonym for domicile. Hence, he concludes that birthright tourism can be excluded but he concludes that it will be difficult to exclude birthright citizenship to illegal aliens who live here and have babies. He confirms that citizenship by birth is defined by the Constitution and may not be restricted by Congress, although Congress is certainly free to liberalize the requirements of citizenship by naturalization.