In America there is the Bill of Rights, or something like that, which makes it very unlikely that a personal computer could be investigated without good reason.
It's the fourth amendment to the us constitution
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.