Briefly: Protection from unreasonable search and seizure
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
According to the government, the 4th Amendment does not apply to American citizens within 100 miles of our northern and southern borders.
First, it's 100 miles, then it's 200 miles. This is how tyranny slithers in the back door, folks.