To analogize to a conventional trespass, a trespass committed by a person walking onto prohibited land would be no less a trespass if that person also happened to invade other nearby properties as well during his travels. Similarly, a pedestrian’s physical presence on the land constitutes a trespass regardless of whether he was there as part of an exercise routine utterly lacking a message, or whether he was there to make a point about something. Whether that person also trespassed onto other properties along the way, and whether his trespass was with, or free of, communicative purpose, are fundamentally irrelevant to whether a trespass occurred …

The [property owners] argue that the beam of light itself is, by definition, a “tangible” thing that can “invade” real property. … But what does it really mean to say that something is “tangible” or amounted to a “physical” invasion? … [The owners’ argument] is that the light projection constituted a trespass because light is composed of “particles” (according to the Encyclopedia Britannica, which the [owners] cite in their brief), and those particles are tangible and therefore capable of physically intruding across the [owners’] property line. But whether something is “tangible” or not does not seem to me to be a proper or clear legal test, at least not one that can be readily understood and applied to a wide range of facts.

Instead, the argument strikes me as a syllogism based upon superficial pseudo-science, and I am not sure that the outcome of this case ought to be governed by this kind of approach.

As an initial observation, the science relied upon by the [owners] appears to be wrong, or at least incomplete. If one really wants to get into the physics of the question, light has the properties of both a wave and a particle. …

More fundamentally, technical merit aside, scientific analysis and legal analysis are two different modes of inquiry designed to accomplish very different goals. … Even if it were unequivocally true that a quantum physicist would think of light as formed of particles, that conclusion alone should not govern whether we should find a trespass here as a matter of legal analysis and underlying public policy. …

Properly framed, I think the question before us is not whether light is tangible or not, but instead: what legal right inherent in property ownership does the light projection supposedly violate? …

Fundamentally, the right to own property is the right to exclude others from entering, using, or possessing it. In a real sense, whenever property is bought or sold, what has really been purchased is the right to sue someone in court for trespass for entering, using, or possessing the property without the owner’s permission. …

We are confronted with a clash between very old law and evolving new technology. Trespass is one of the oldest torts known to Anglo-American jurisprudence, dating as far back as twelfth-century England. But back then, even the most advanced thinkers of the day were not aware of such things as atoms, electrons, or photons. …

It should come as no surprise, therefore, that the tort of trespass was originally limited to physical invasions of property by people or objects composed entirely of matter. … In an era lit by wax candles, and then whale-oil lamps, and then kerosene, there was not much that one could do to another’s property with light. But nowadays light can be so many more things and can be used in so many more ways; searchlights, lasers, and light projectors of the kind involved in this case are now commonplace. The inquiry here is whether the bundle of rights traditionally protected by the ancient tort of trespass should be read to include the right to stop the newly-developed light projection used here.