A legal adage dating at least to the early 1800s is, “Hard cases make bad law.” Interpretations of this maxim have produced many variants, one being that complex cases — cases involving conflicting fundamental principles — often result in a “Solomon’s choice” of being forced to “halve the baby,” that is, to have to choose between two fundamental principles. Hence the “bad law” piece: When fundamental principles are in direct opposition, at least one of them will lose — maybe both.

So is the potential in this week’s 5-4 U.S. Supreme Court decision in Carpenter v. United States that warrantless tracking by law enforcement of a cellphone user’s location via carrier records violates the Fourth Amendment. The principles at odds: On the one hand, law enforcement’s legitimate interest in catching criminals through the use of information over which the surveilled individual has no reasonable expectation of privacy; on the other, an individual’s fundamental Fourth Amendment right against unreasonable government searches and seizures.

The factual background of the case centers on the FBI’s use of the cellphone records of a suspected armed robber, Timothy Carpenter, to identify cell towers used in Carpenter’s alleged robberies and then to use geolocation techniques to fix his position during the periods in which the robberies were committed. Carpenter was convicted, in part, on the basis of that information, which fixed him at the locations and times of the robberies.

In an unusual split, Chief Justice John Roberts sided with the left wing of the Court (Justices Stephen Breyer, Ruth Bader Ginsburg, Elena Kagan and Sonia Sotomayor). The Court’s punchline: “We hold that an individual maintains a legitimate expectation of privacy in the record of his physical movements as captured through [cell site location information].” That is, notwithstanding the substantial body of Court precedents allowing law enforcement’s virtually unfettered access to third-party-owned information on an individual, this week’s Court drew a line in the sand on… what, exactly? That’s the real question, then — isn’t it?

Beyond the muck that is today’s Fourth Amendment jurisprudence, this week’s decision muddied the waters even further. Legacy Court cases had definitively determined, for example, that “a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties” — like, maybe, cellphone records held by cellphone service providers, for instance? Well, yes … (ahem) … that is, no: “pen-register data” — today, so-called “metadata” — about what calls were placed from where and when? That is all well-and-good. So getting data about calling patterns is okay. But location data? No. Can’t do that. Get it?

Now, of course law enforcement officials can surveil and track an individual all over their jurisdiction (i.e., the entire U.S., in the case of the FBI, as here) without so much as a whiff of a search warrant in the air, as long as the individual travels along venues in which the individual enjoys no reasonable expectation of privacy (think: From the moment you leave your home until the moment you return, 99% of the time). But using metadata to perform that same function is, um, bad. Stay with us — it gets better.

Justice Anthony Kennedy — that liberal-conservative, quantum-wavering strobe — in a flash of unexpected brilliance produced an actually salient fact: “Cell-site records … are no different from the many other kinds of business records the Government has a lawful right to obtain by compulsory process. Customers like petitioner do not own, possess, control, or use the records, and for that reason have no reasonable expectation that they cannot be disclosed pursuant to lawful compulsory process.” Very true.

So, so far it would appear we’re coming down solidly on the side of the majority.

But wait: What about the counterarguments? Might those matter? Justice Clarence Thomas, for instance, dropped this safe on the majority decision: “This case should not turn on ‘whether’ a search occurred. It should turn, instead, on whose property was searched.” Joined in his dissent by Justices Kennedy, Samuel Alito and Neil Gorsuch, Thomas goes on to make the case that the cell-site records were not Carpenter’s, but rather those of his cellphone service providers, and thus Carpenter had no reasonable expectation of privacy in the location information disclosed by the records. But this wasn’t the only forceful challenge to the majority opinion.

Gorsuch took an entirely different tack, stating, “It seems to me entirely possible a person’s cell-site data could qualify as his papers or effects under existing law.” In other words, if the metadata were to be classified by law as belonging to the individual, then a search warrant would be required. The dissent was not joined, but nonetheless poses a very intriguing question to future Fourth Amendment cases involving metadata, namely, data ownership rights and right-to-privacy issues regarding the same.

So where does Fourth Amendment jurisprudence stand? Who knows?

Carpenter lost in the lower courts based on Supreme Court precedents holding that phone customers have no right to expect the numbers they dial will remain private because their carriers own that data, not them. But Carpenter’s lawyers argued those precedents are outdated since telephones had fixed locations when those precedents were decided and today’s highly mobile users expect their calling locations to remain private. Really? Should they? But since cellphone metadata enables law enforcement officials to discover much more information than simply which numbers were dialed — e.g., exact times of calls, 24/7 coverage, geolocations within very small distances, etc. — and since almost all of us own a cellphone, this Fourth Amendment issue should be important to virtually every American. Even so, this week’s halving-the-baby decision simply can’t be the final answer — too many values and principles are at stake.