The Fourth Amendment says, “all persons shall be secure in their persons, houses, papers, and effects from unreasonable searches and seizures, and no warrants shall issue, but upon probable cause, before a magistrate and upon Oath, specifically describing the persons to be searched and places to be seized.”
The court has read the Fourth Amendment to prohibit only those government searches or seizures that are “unreasonable.” Because of this, businesses that are in an industry that is “closely regulated” can be searched more frequently and can be searched without a warrant. In one case, an auto parts dealer at a junkyard was charged with receiving stolen auto parts. Part of his defense was to claim that the search that found incriminating evidence was unconstitutional. But the court found the search reasonable, because the dealer was in a “closely regulated industry.”
In the 1980s, Dow Chemical objected to an overflight by the US Environmental Protection Agency (EPA). The EPA had rented an airplane to fly over the Midland, Michigan, Dow plant, using an aerial mapping camera to photograph various pipes, ponds, and machinery that were not covered by a roof. Because the court’s precedents allowed governmental intrusions into “open fields,” the EPA search was ruled constitutional. Because the literal language of the Fourth Amendment protected “persons, houses, papers, and effects,” anything searched by the government in “open fields” was reasonable. (The court’s opinion suggested that if Dow had really wanted privacy from governmental intrusion, it could have covered the pipes and machinery that were otherwise outside and in open fields.)
Note again that constitutional guarantees like the Fourth Amendment apply to governmental action. Your employer or any private enterprise is not bound by constitutional limits. For example, if drug testing of all employees every week is done by government agency, the employees may have a cause of action to object based on the Fourth Amendment. However, if a private employer begins the same kind of routine drug testing, employees have no constitutional arguments to make; they can simply leave that employer, or they may pursue whatever statutory or common-law remedies are available.