What are the origins and original purposes of searches and seizures.
The origin of "Search and Seizures" as we know it / the purposes today is in the Fourth Amendment of the US Constitution!
The Fourth Amendment says:
"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."
See Source 1
WHY did the writers of the Constitution feel the need for this Amendment?
At the time, the British still controlled (what we know as the US today) the colonies. British colonials and those in charge could search ANY home, and seize ANY item they desired, without even a REASON or cause to search. This "right" the British had under the crown was called "Writs of Assistance" but were basically just general warrants with no rhyme or reason.
Because the founders of our Constitution felt so violated by these random searches and seizures (meaning the British could then TAKE -- STEAL -- anything they found worthwhile), they created the Fourth Amendment--in response.
Re-Read the Fourth Amendment I've typed up top there--see how it says that the colonies were PROTECTED from UNREASONABLE search/seizures, without PROBABLE cause (a "likelyhood that there was something illegal"), the British ways of random searches were no longer implemented as the colonies gained freedoms.