From Wikipedia:
http://en.wikipedia.org/wiki/Freedom_of_movement-snip-
United States
In the United States, no specific law guarantees this right, but the Supreme Court of the United States has held in a number of cases that such a right necessarily exists. In Kent v. Dulles, 357 U.S. 116 (1958), the United States Secretary of State had refused to issue a passport, based on the suspicion that the plaintiff was going abroad to promote communism. Justice William O. Douglas wrote for the Court:
The right to travel is a part of the 'liberty' of which the citizen cannot be deprived without due process of law under the Fifth Amendment. . . . Freedom of movement across frontiers in either direction, and inside frontiers as well, was a part of our heritage. Travel abroad, like travel within the country, . . . may be as close to the heart of the individual as the choice of what he eats, or wears, or reads. Freedom of movement is basic in our scheme of values.
The U.S. Supreme Court dealt with the right of interstate travel most recently in the case of Saenz v. Roe, 526 U.S. 489 (1999). In that case, Justice John Paul Stevens, writing for the majority, held that the United States Constitution protected three separate aspects of the right to travel among the states: the right to enter one state and leave another, the right to be treated as a welcome visitor rather than a hostile stranger (protected by the Privileges and Immunities Clause in Article IV, §2), and for those who become permanent residents of a state, the right to be treated equally to native born citizens (this is protected by the 14th Amendment Privileges or Immunities clause).
The issue of freedom of movement has received new attention in the United States as of 2004; in particular, concerning the methods and internal practices of the Transportation Security Administration.
Another issue of contention deals with freedom of movement across U.S. national borders. The United States has long been lax in permitting persons to cross from Canada into the United States. Concerns about drug trafficking and illegal immigrants seeking employment have led to much stricter controls on those crossing the border from Mexico.
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