Imagine that you own a small hotel or motel. One weekend, a group booking arrives and checks in. While taking their IDs and license-plate information, you discover that they're visiting town to attend a political conference the following day. If you're a conservative, imagine that they're Tea Partiers or NRA members. If you're a liberal, think of them as Occupy Wall Street protesters or anti-war activists. Now imagine that an hour, or a day, or two weeks later, a police officer shows up demanding to see all the information you collected from those customers. He has neither a warrant nor any evidence that the guests committed a crime. As a hotel or motel owner, should you be compelled to turn over their information?

The Supreme Court will soon address that question. It agreed this week to hear the case of Patel vs. City of Los Angeles, which touches on two municipal laws. One of the laws "requires hotel and motel operators to collect and record detailed information about their guests in either paper or electronic form. The records must contain: the guest’s name and address; the number of people in the guest’s party; the make, model, and license plate number of the guest’s vehicle if the vehicle will be parked on hotel property; the guest’s date and time of arrival and scheduled date of departure; the room number assigned to the guest; the rate charged and the amount collected for the room; and the method of payment."

That law is not being challenged, though perhaps it ought to be. Instead, hotel and motel owners are objecting to a related law, which requires them to share all that information with any LAPD officer who requests it. "The city stipulated that this provision authorizes police officers to inspect hotel guest records at any time without consent or a search warrant," the Ninth Circuit Court of Appeals noted in its opinion. "Failure to comply with an officer’s inspection demand is a misdemeanor, punishable by up to six months in jail and a $1000 fine."

Los Angeles and its police department are plainly violating the Fourth Amendment rights of hotel and motel owners, as the federal appeals court found. Perhaps the Supreme Court will uphold or even broaden the Ninth Circuit decision.

Meanwhile, it is worth stepping back to think through the alarming logic embraced by the City of Los Angeles, the LAPD, a district court, and a dissent in the Ninth Circuit. It begins with the notion that hotel and motel guests have no right to privacy in information that they voluntarily turn over to third parties, per Smith v. Maryland. That precedent is problematic on its own. But it is devastating to privacy when paired with laws that compel business owners to collect detailed information on customers and to turn it over without warrants.

The effect of this logic is that Americans cannot travel without waiving privacy rights to personal details as intimate as where we go, the times we arrive and leave, who stays with us in our room, and how many beds are inside that room. If the state is permitted to seize all that information without probable cause or a warrant, the Fourth Amendment is worthless, at least if the same logic is extended to other businesses. After all, most people can't function in modern American society without revealing virtually every aspect of their lives to some "third party" or other.

The Supreme Court ought to rule against the City of Los Angeles. But regardless of the outcome, voters should start ousting from office the policymakers who keep expanding a coercive surveillance state, all to spare police officers some paperwork. Without probable cause, the government has no business snooping into these records. And with probable cause, a warrant is but a judge's signature away.