The Supreme Court handed down Collins v. Virginia today, ruling 8-1 that the Fourth Amendment doesn't permit the police to go onto the curtilage around a home to search a car using the lower standard of the automobile exception. The decision was 8-1, with Justice Sotomayor writing for the majority and Justice Alito dissenting. I think the majority was exactly right: The automobile exception allows a search of a car once you're at the car, but it doesn't allow entrance onto the curtilage (treated as the home for Fourth Amendment purposes) to get to the car to then apply the automobile exception. And I think Justice Sotomayor wrote a strong opinion on it, too.

To my mind, the most interesting aspect of Collins concerns a brief preliminary part of the decision, the Court's identification of the curtilage. As Fourth Amendment nerds know, curtilage is the space immediately around the home that gets treated as an extension of the home for Fourth Amendment purposes. As I teach the concept in class, the law needs curtilage because otherwise the police could go right up to someone's windows and peer inside without it being a Fourth Amendment "search." Curtilage creates a sort of buffer around the home to make sure the home is fully protected fro observation.

This raises a puzzle, how do you identify the curtilage? The Court seems to go back and forth between thinking it's easy and thinking it's hard. Recent cases suggest the concept is easy and intuitive, but I wonder if that is true. I thought I would explain the basis for my sketpicism.

Here's a history of the curtilage concept to bring us up to speed. The Court first hinted at the idea of curtilage in Hester v. United States, 265 U.S. 57 (1924), a short and breezy opinion by Justice Holmes. Officers found booze on land not far from the suspect's house. Held: This was a search of an "open field" not protected by the Fourth Amendment, as by its text the Fourth Amendment only protects "persons, houses, papers and effects"":

This evidence was not obtained by the entry into the house, and it is immaterial to discuss that. The suggestion that the defendant was compelled to give evidence against himself does not require an answer. The only shadow of a ground for bringing up the case is drawn from the hypothesis that the examination of the vessels took place upon Hester's father's land. As to that, it is enough to say that, apart from the justification, the special protection accorded by the Fourth Amendment to the people in their "persons, houses, papers and effects" is not extended to the open fields. The distinction between the latter and the house is as old as the common law. 4 Bl.Comm. 223, 225, 226.

The citation to Blackstone was to Blackstone's discussion of the substantive crime of burglary. It included at page 225 the following sentence:

And if the barn, ftable, or warehoufe be parcel of the manfionhoufe, though not under the fame roof or contiguous, a burglary may be committed therein; for the capital houfe protects and privileges all it's branches and appurtenants, if within the curtilage or homeftall.

The bafic idea—um, I mean, basic idea—was that you were still guilty of burglary if you broke into a barn, stable, or warehouse that was a part of the house area even if not under the same roof as the home. Hester then suggests that Fourth Amendment law has a similar concept, with some area around the home being protected as part of the home but not open fields.

The Court then reaffirmed Hester after Katz in Oliver v. United States, 66 U.S. 170 (1984), incorporating and expanding upon the distinction between open fields and curtilage in the era of the "reasonable expectation of privacy: test:

In Oliver, the police observed marijuana growing in a secluded field surrounded by wood and fences with "no trespassing" signs put up: The field could not be seen from any point of public access. The Court ruled that the field was still an "open field" for Fourth Amendment purposes:

The test of legitimacy is not whether the individual chooses to conceal assertedly "private" activity. Rather, the correct inquiry is whether the government's intrusion infringes upon the personal and societal values protected by the Fourth Amendment. As we have explained, we find no basis for concluding that a police inspection of open fields accomplishes such an infringement.

The Oliver court added in a footnote that the distinction should be relatively easy to draw in most cases:

The clarity of the open fields doctrine that we reaffirm today is not sacrificed, as the dissent suggests, by our recognition that the curtilage remains within the protections of the Fourth Amendment. Most of the many millions of acres that are "open fields" are not close to any structure and so not arguably within the curtilage. And, for most homes, the boundaries of the curtilage will be clearly marked; and the conception defining the curtilage — as the area around the home to which the activity of home life extends — is a familiar one easily understood from our daily experience. The occasional difficulties that courts might have in applying this, like other, legal concepts, do not argue for the unprecedented expansion of the Fourth Amendment advocated by the dissent.

Three years after Oliver, in United States v. Dunn, the Court offered a rather challenging 4-factor test to draw the line between protected curtilage and unprotected open fields:

Drawing upon the Court's own cases and the cumulative experience of the lower courts that have grappled with the task of defining the extent of a home's curtilage, we believe that curtilage questions should be resolved with particular reference to four factors: the proximity of the area claimed to be curtilage to the home, whether the area is included within an enclosure surrounding the home, the nature of the uses to which the area is put, and the steps taken by the resident to protect the area from observation by people passing by. See California v. Ciraolo, 476 U. S. 207, 476 U. S. 221(1986) (POWELL, J., dissenting) (citing Care v. United States, 231 F.2d 22, 25 (CA10), cert. denied, 351 U.S. 932 (1956); United States v. Van Dyke, 643 F.2d 992, 993-994 (CA4 1981)). We do not suggest that combining these factors produces a finely tuned formula that, when mechanically applied, yields a "correct" answer to all extent-of-curtilage questions. Rather, these factors are useful analytical tools only to the degree that, in any given case, they bear upon the centrally relevant consideration—whether the area in question is so intimately tied to the home itself that it should be placed under the home's "umbrella" of Fourth Amendment protection.

Dunn applied those factors to hold that the area near a barn, located approximately 50 yards from a fence surrounding a ranch house, on a rural property itself surrounded by fences and some barbed wire, was part of open fields and not curtilage.

Contrast that with the more recent discussions of curtilage, which treat it as easy and intuitive. In Florida v. Jardines (2013), the Court held that the front porch of a home is curtilage rather than open fields. Writing for the Court, Justice Scalia suggested that this was obvious:

We . . . regard the area "immediately surrounding and associated with the home"—what our cases call the curtilage—as "part of the home itself for Fourth Amendment purposes." Oliver, supra, at 180. That principle has ancient and durable roots. Just as the distinction between the home and the open fields is "as old as the common law," Hester, supra, at 59, so too is the identity of home and what Blackstone called the "curtilage or homestall," for the "house protects and privileges all its branches and appurtenants." 4 W. Blackstone, Commentaries on the Laws of England 223, 225 (1769). This area around the home is "intimately linked to the home, both physically and psychologically," and is where "privacy expectations are most heightened." California v. Ciraolo, 476 U. S. 207, 213 (1986) . While the boundaries of the curtilage are generally "clearly marked," the "conception defining the curtilage" is at any rate familiar enough that it is "easily understood from our daily experience." Oliver, 466 U. S., at 182, n. 12. Here there is no doubt that the officers entered it: The front porch is the classic exemplar of an area adjacent to the home and "to which the activity of home life extends." Ibid.

That brings us to today's decision, Collins, which applies the concept of curtilage to a driveway. Here's the relevant part of the opinion:

According to photographs in the record, the driveway runs alongside the front lawn and up a few yards past the front perimeter of the house. The top portion of the driveway that sits behind the front perimeter of the house is enclosed on two sides by a brick wall about the height of a car and on a third side by the house. A side door provides direct access between this partially enclosed section of the driveway and the house. A visitor endeavoring to reach the front door of the house would have to walk partway up the driveway, but would turn off before entering the enclosure and instead proceed up a set of steps leading to the front porch. When Officer Rhodes searched the motorcycle, it was parked inside this partially enclosed top portion of the driveway that abuts the house. The "'conception defining the curtilage' is . . . familiar enough that it is 'easily understood from our daily experience.'" Jardines, 569 U. S., at 7 (quoting Oliver, 466 U. S., at 182, n. 12). Just like the front porch, side garden, or area "outside the front window," Jardines, 569 U. S., at 6, the driveway enclosure where Officer Rhodes searched the motorcycle constitutes "an area adjacent to the home and 'to which the activity of home life extends,'" and so is properly considered curtilage, id., at 7 (quoting Oliver, 466 U. S., at 182, n. 12).

Googling around, I found a news story that appears to include one of the photographs Justice Sotomayor describes:

Especially looking at the photograph, the Court's result seems clearly right. Seeing the photo, the space seems, well, private: It wasn't just a driveway, but rather was a space that happened to be paved that was right up aginst the house in an area enclosed by walls. (As an aside, I think all curtilage decisions should include a photograph if one is availbale in the record: It makes these cases much easier to understand.)

I go through all of this because I wonder if curtilage is as easy as the Court suggests. Here, I agree it's pretty easy. But what about other common cases? For example, imagine the more routine case of a car parked in a driveway in front of a house. Maybe the car is parked in front of an attached garage, or perhaps it is in front of a detached garage some yards from the house. Should that be an easy curtilage issue under Collins, or should it get a complex 4-factor analysis under Dunn? Is Collins just about the special case of a space enclosed by walls right up to the house that happens to be a driveway, or is it a general ruling that applies to driveways?

More broadly, I wonder if curtilage is really "easily understood from our daily experience." Here's the question: If you showed people pictures of different houses, and asked if a particular spot near any particular house was curtilage—explaining the test to them, not giving them the label—would there be rough consensus or would opinions be all over the map? It wouldn't be all that hard to come up with such an experiment, and it would be really interesting to know whether the Court's assumptions about what "daily experience" teaches are widely shared.