13.5 Trespass to Land

Trespass to Land

Doctrinal Foundation: Intentional torts to property protect possessory and proprietary interests in real property (land, structures, and fixtures) and personal property (chattels). On the California First-Year Law Students' Examination (FYLSE), property torts test your ability to separate land invasions from intangible nuisances, enforce the strict rule that good-faith mistake does not excuse trespass, apply the vertical boundaries of real property, and delineate the sharp boundary between Trespass to Chattels (requiring actual damage, with damages measured by repair or loss of use) and Conversion (warranting a forced judicial sale for full market value).

---

I. Trespass to Land (Quare Clausum Fregit)

Trespass to land protects the plaintiff's interest in the exclusive possession of real property. It is an action vindicating possession rather than ownership; a tenant in lawful possession can maintain trespass against anyone, including the legal landlord.

The Prima Facie Elements

To establish a prima facie case of trespass to land, the plaintiff must prove:

1. An act of physical invasion of real property;
2. Intent to bring about a physical invasion of the land; and
3. Lawful possession of the real property by the plaintiff.

                         ┌──────────────────────────────────────┐
                         │   Prima Facie Case: Trespass to Land │
                         └──────────────────┬───────────────────┘
                                            │
         ┌──────────────────┬───────────────┴───────────────┬──────────────────┐
         ▼                  ▼                               ▼                  ▼
    [PHYSICAL INVASION] [INTENT]                        [REAL PROPERTY]    [NO INJURY NEEDED]
- Defendant enters   - Intent to enter THAT space       - Surface, subsurface - Actionable per se
- Causes object to   - Mistake of boundary is           - Lower airspace      - Nominal damages
  enter land           NO DEFENSE                         (Causby rule)         presumed to protect
- Fails to remove    - Transferred intent applies       - Lawful possession     title/possession

1. The Nature of the Physical Invasion

A physical invasion occurs whenever the defendant:

• Enters the land in person without consent;
• Propels, throws, or projects a tangible physical object onto the land (e.g., throwing rocks across the boundary, shooting bullets over the parcel, chasing livestock onto the land, or grading soil such that dirt spills onto the neighbor's lot);
• Causes a third person to physically enter the property;
• Remains on the land after lawful permission, license, or lease has expired;
• Fails to remove an object from the land after a legal duty to remove it has arisen (e.g., leaving building materials on a neighbor's driveway after completing an agreed repair).

[!WARNING] Tangible Invasions vs. Intangible Intrusions (Trespass vs. Nuisance): Trespass to land strictly requires an invasion by a tangible physical mass or object. Intangible intrusions—such as microscopic smoke, toxic odors, noxious chemical fumes, loud noise, bright lights, or seismic vibrations—do NOT constitute trespass to land. Instead, intangible interferences with the use and enjoyment of land are actionable exclusively under private nuisance or negligence, unless the particles accumulate as visible, tangible deposits on the soil.

2. The Intent Requirement: Mistake Is No Defense

The intent required for trespass to land is merely the intent to enter or be present on that specific physical space:

• No Intent to Trespass Required: The defendant does not need to know that the land belongs to another, nor intend to cross a legal boundary.
• The Absolute Rule on Mistake of Fact: A good-faith, reasonable mistake as to ownership, boundary lines, or legal permission is NO DEFENSE. If an individual purchases land, hires a surveyor who mistakenly places boundary stakes ten feet into the neighbor's property, and the individual erects a fence or walks on that strip, the individual is liable for trespass to land (Perry v. Jefferies).
• Involuntary Physical Invasions: If an actor is thrown onto the land by third parties, or suffers an involuntary epileptic seizure and collapses across the property line, there is no trespass to land because there was no volitional intentional act.

3. Vertical Scope of Real Property: Airspace and Subsurface

At early common law, real property ownership was governed by the maxim cuius est solum, eius est usque ad coelum et ad inferos ("whoever owns the soil owns up to the heavens and down to the depths"). Modern American jurisprudence applies a more functional standard:

• Subsurface Rights: The possessor owns the subsurface to a reasonable depth. Horizontal subterranean mining, oil drilling, or running utility lines beneath another's soil without an easement constitutes a physical trespass.
• Airspace Rights (United States v. Causby, 328 U.S. 256 (1946)): The possessor owns the lower airspace immediately above the surface to the extent that the possessor can occupy or make practical use of it in connection with the land. High-altitude commercial aircraft flights do not constitute trespass. However, low-altitude flights, overhanging roof eaves, protruding tree limbs, utility lines strung over a yard, or low-flying surveillance drones that interfere with the owner's immediate use and enjoyment constitute actionable trespass to land.

4. Damages

Trespass to land is actionable per se. The plaintiff does not need to prove actual physical harm, diminution in value, or disruption. Nominal damages are recoverable automatically to vindicate the possessory right and prevent the trespasser from acquiring a prescriptive easement.

---