MarcusEmma, welcome back to Office Hours. I have a scenario for us today. It feels very real, and it's exactly the kind of thing we'd see on the exam.
EmmaLet’s do it.
MarcusState police get an anonymous tip about a house. Without a warrant, they fly a drone with a thermal camera over it. The camera picks up heat signatures that suggest marijuana grow lamps inside. They use that thermal data to get a warrant, search the house, and make an arrest.
EmmaA classic fact pattern.
MarcusThe homeowner challenges that initial drone surveillance. So the core question is: did that warrantless thermal scan violate the homeowner's constitutional privacy rights?
EmmaThat's the perfect question to frame this topic, because it forces us to go back to the source. The first thing to remember is that the U.S. Constitution doesn't have a sentence that explicitly says, "You have a right to privacy."
MarcusIt doesn't? I think a lot of people assume it does. So where does this right come from?
EmmaIt's an implied right. It's primarily drawn from two places. First, the Fourth Amendment. And second, a concept called 'penumbral rights.' And crucially, both of these limit the actions of the government, not private companies.
MarcusOkay, so this is all about what the government can and cannot do. Let’s start with the big one, the Fourth Amendment. What is its core purpose?
EmmaIts text protects people from "unreasonable searches and seizures." For a search to be reasonable, the government generally needs a warrant based on probable cause. The whole analysis hinges on whether a person had a "reasonable expectation of privacy."
Marcus"Reasonable expectation of privacy." That phrase seems to carry a lot of weight, but it also sounds a bit vague. How does a court determine what's 'reasonable'?
EmmaThey use a two-part test that came out of a major Supreme Court case, Katz v. United States. It’s a case that really shifted the focus from physical property to a person’s expectation of privacy.
MarcusA two-part test. What’s the first part?
EmmaFirst, did the individual show that they actually expected privacy? This is the subjective part. Did they act like they wanted to keep something private?
MarcusSo, like closing the blinds in your house, or putting a password on a file. You’re taking a step to signal "this is private."
EmmaExactly. That's the subjective expectation.
MarcusAnd the second part of the test?
EmmaThe second part is objective: Is that expectation of privacy one that society is prepared to recognize as reasonable? This is where the debate always is, especially when new technology is involved.
MarcusSo even if I think something is private, society might not agree. And that's where the courts have to draw a line.
EmmaPrecisely. It’s not just about what you believe, but about what we as a society agree is a fair expectation.
MarcusYou also mentioned another source for the right to privacy: 'penumbral rights.' That sounds pretty academic. What does it mean in a practical sense?
EmmaIt does sound academic, but the idea is fairly concrete. It comes from another landmark case, Griswold v. Connecticut. The Supreme Court said that even though privacy isn't mentioned by name, several amendments in the Bill of Rights cast 'penumbras.' These are like shadows that create zones of privacy.
MarcusShadows? Like the rights in the amendments imply other, unstated rights?
EmmaThat's the idea. Think of it like this: the explicit rights are bright lights. The penumbra is the halo of light around them. The court pointed to several amendments. For example, the First Amendment's freedom of association. The Third, which stops soldiers from being quartered in homes. And the Fourth and Fifth Amendments. Together, they create this broader zone of personal privacy.
MarcusSo the Fourth Amendment protects my house and my papers, but these other amendments together protect more personal aspects of my life?
EmmaYes. The court used this concept to protect fundamental decisions about things like marriage, procreation, and contraception. It’s a different flavor of privacy than the search-and-seizure context of the Fourth Amendment.
MarcusOkay, so we have these protections from government intrusion. But they can’t be absolute. What’s the biggest limitation we need to know for the exam?
EmmaThe third-party doctrine. This is a huge concept. The basic idea is that you lose your reasonable expectation of privacy in information that you voluntarily give to a third party.
MarcusSo if I deposit a check at my bank, the government can get my bank records from the bank without a warrant, because I voluntarily used the bank?
EmmaUnder the traditional doctrine, yes. That's from a case called United States v. Miller. Another case, Smith v. Maryland, said the same thing about the phone numbers you dial. You give them to the phone company, so you don't have an expectation of privacy in them.
MarcusThat feels… outdated. I have to use a bank. I have to use a phone. Am I really 'voluntarily' giving up my privacy just by participating in modern life?
EmmaYou've hit on the exact reason this doctrine is so controversial today. And the Supreme Court has started to agree with your line of thinking. In a more recent case, Carpenter v. United States, the Court changed its thinking. It said that people do have a reasonable expectation of privacy in their historical cell-site location information.
MarcusSo my phone's location data.
EmmaRight. The Court recognized that tracking your location for weeks or months reveals an incredible amount of private detail about your life. So they carved out an exception, saying the government needs a warrant for that kind of data. It shows the third-party doctrine isn't a simple, absolute rule anymore.
MarcusThis is a great framework. Let's go back to our opening scenario and apply it. The police drone with the thermal imager over the house. How do we break it down?
EmmaWe can use a step-by-step analysis, which is perfect for the exam. Step one is to identify the actor.
MarcusThat's the state police, so it's a government actor. The Fourth Amendment is definitely in play.
EmmaCorrect. Step two: did a 'search' even happen? We apply that two-part Katz test. Did the homeowner have a subjective expectation of privacy inside their house?
MarcusOf course. It’s their home. You expect what happens inside, stays inside.
EmmaRight. Now for the objective part: does society recognize that expectation as reasonable? Is it reasonable to expect that the government isn't using high-tech thermal cameras to see the heat patterns inside your home?
MarcusI would say yes, absolutely. It feels different from an officer just looking at the house from the street. This is technology that sees something you can't see with the naked eye.
EmmaExactly. And this is the key question for the objective part of the test. You'd argue that society considers it unreasonable for the government to use high-tech cameras to see heat patterns inside a home. It's not something the public can do. It goes beyond what a person knowingly exposes to the world. So, under our analysis, we would argue that a search did occur.
MarcusOkay, so what’s next in the analysis?
EmmaStep three is assessing the context, which we've really already done. The expectation of privacy is at its absolute highest in a person's home. Step four, the third-party doctrine, doesn't apply here at all. The homeowner didn't share their home's heat signature with anyone.
MarcusThat leaves the final step. Was the search reasonable?
EmmaA search of a home is generally presumed to be unreasonable without a warrant. Here, the police conducted the thermal scan before they got a warrant. In fact, they used the scan to get probable cause for the warrant. So, the argument would be that the initial drone surveillance was an unreasonable search. And that it violated the Fourth Amendment.
MarcusThat makes perfect sense when you walk through it logically. But I can see how the exam could set traps here. What's the most common one?
EmmaBy far, the biggest trap is applying these constitutional rules to private companies. If a news organization or a private investigator flew that same drone, it wouldn’t be a Fourth Amendment issue. It might be a different kind of legal violation, based on other statutes, but the Constitution's privacy protections are a limit on the government.
MarcusSo, first question on the exam should always be: is the government the one doing the action?
EmmaAlways. Another trap is oversimplifying the "reasonable expectation of privacy." Just because you’re in public doesn’t mean you have zero privacy. Katz was about a conversation in a public phone booth. The Court is looking at the context, not just whether a space is public or private property.
MarcusAnd that third-party doctrine feels like a potential minefield, especially with the Carpenter case.
EmmaIt is. The trap is to think it's an all-or-nothing rule. The exam will test if you understand the traditional rule from Miller and Smith. But it will also test if you know that Carpenter shows the courts are reconsidering that rule. Especially for new kinds of pervasive digital data.
MarcusThis is a lot to hold in your head. We have Katz, Griswold, Carpenter, and the step-by-step framework. It's a dense topic. Let's do a quick recap of the absolute must-know points.
EmmaFirst, the Fourth Amendment protects against unreasonable searches and seizures by the government.
MarcusAnd the key test for a 'search' comes from Katz. It's a subjective expectation of privacy that society agrees is objectively reasonable.
EmmaCorrect. Second, remember penumbral rights. That’s the idea from Griswold that 'zones of privacy' are implied by other amendments, protecting personal decisions.
MarcusGot it. Third is the third-party doctrine. We lose our expectation of privacy for information we voluntarily share.
EmmaBut—and this is critical—remember that cases like Carpenter are creating important exceptions. Especially for modern, pervasive digital tracking.
MarcusAnd the final, most important takeaway?
EmmaIt's about government action only. These constitutional protections apply to government actors. They do not apply to private companies, unless that company is acting as an agent for the government.
MarcusThat's a perfect summary. Thanks, Emma.
VoraPrep is a full exam-prep app — lessons, practice questions, and an AI tutor in one place. Get started at Vora Prep dot com.