Amendment IV of the U. S. Constitution: The right of the people to be secure in their persons, houses, papers, and effects, 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.
the question hinges on whether the electronic emanations from your device are ‘your effects’. evidently the nsa believe its not and regard it as free for the taking.