In cases of trespass, there are some defenses available to the defendant to justify the trespass.  However, ignorance or mistake of law or fact is not an excuse for trespass[i].

One of the defenses is the title and possession of the property[ii].  To invoke this defense, the person must have the actual ownership of property along with the title.  The person in actual possession has the right to maintain an action for trespass against all persons other than the original owner[iii].  Thus, a trespass is privileged if the defendant is a bonafide purchaser, and has an ownership claim over the property.

An action for trespass may not be entertained where the defendant has acquired a right of easement.  An easement is the right to use the real property of another without possessing it.  But the defendant is liable, if s/he exceeds or misuses the extent and scope of the right.  In Phillips v. Jacobsen, 117 A.D.2d 785 (N.Y. App. Div. 2d Dep’t 1986), the court observed that an easement granted in general terms must be construed to include any reasonable use which is lawful and is contemplated by the court.

The statute of limitations is a defense that is ordinarily asserted by the defendant to defeat an action brought against him/her after the appropriate time has elapsed.  The defendant has to prove the entitlement to limitations.

The doctrine of estoppel is an important defense to the action of trespass.  Estoppel arises when a person who had a duty to speak or act, intentionally or negligently made another through his/her action or silence to believe in the existence of a fact that does not exist, and another acted by relying on such an act or omission[iv].  The doctrine of estoppel is not applicable if the defendant has consented to it.

Apart from the defenses above mentioned, there are some exceptions.  Infancy is not considered as a defense for the liability of trespass.  The plaintiff’s conduct and contributory negligence can be taken into consideration to determine if a trespasser was entitled to enter a land to claim chattel.  However, it is not a ground for defense.

An action will not amount to trespass if it is privileged.  People who commit trespass may not be liable if they have a legal defense for their actions.  A trespass may occur only when the holder of the privilege acts unreasonably or unnecessarily.  Following are some of the privileges enjoyed by a trespasser:

• Necessity is a privilege against trespass.  A defendant is excused from liability for trespass to land if the action is strictly necessary to prevent public disaster.  The action is not liable if it is for the benefit of the defendant or a third person.  But if they cause any damage while on the property, they could be held liable for any losses.  For example, A, an aviator, while carefully and skillfully operating his/her airplane makes a forced landing on B’s field in the reasonable belief that it is necessary to do so for the protection of himself/herself and his/her plane.  A is not liable for his/her mere entry, but s/he is subject to liability for any harm thereby caused to B or to B’s buildings, crops or other belongings.
• An action will not amount to trespass if the defendant enters another’s property to abate any public or private nuisance.  Any public nuisance which causes harm can be abated and it will not amount to trespass.  The act of the defendant must be reasonable for the purpose of abating a private nuisance.  A public officer who is authorized to abate public nuisance is privileged to enter any person’s land for the same purpose at a reasonable time and manner[v].
• Consent is another common privilege in trespass.  A defendant’s action is privileged if the entry to the land is with the consent or license of the person who has a rightful and legal possession of land.  Consent can be implied from custom, usage or conduct.  The action becomes trespass if it is beyond the scope of the consent or license. The acts of the defendant should not exceed or conflict with the purposes of the consent.  Privilege of consent has to be established by the defendant.  A person who enters a public area in a reasonable time and manner has the implied consent of the owner and his/her action does not amount to trespass.  Consent will not be considered as a privilege to trespass if it is obtained by fraud, misrepresentation or under compulsion[vi].
• A law enforcement officer performing his/her duty in a reasonable manner without causing any harm is privileged to commit a trespass.  A law enforcement officer is privileged to make an entry to arrest or summon up an already arrested person.  Acts of persons like union agents, firefighters, physicians, conservator, power companies and telephone companies are justified under the reason of authority.
• Where a person, with the prior consent of the landowner enters the latter’s land to remove or fix any personal property, enjoys the privilege of trespass.  One is privileged to enter other’s land for the purpose of removing a chattel at a reasonable time and manner without causing any damage.  A person is privileged to enter other person’s land to demand the return of his/her property which is placed or left on the other person’s land.  Moreover, a person can enter another person’s land to return a thing.  A landowner is privileged to remove another’s personal property which is placed on the land illegally.  S/he can exercise this privilege once defendant fails to comply with the landowner’s notice to remove the same[vii].  Landowner shall use due care to remove things that are wrongfully on his/her land.  S/he is privileged only when the action is within the control and extent over the trespassing item as is necessary to remove it.  Finally, the harm caused while exercising the privilege should be reasonable and necessary.

[i] Hobart v. Hagget, 12 Me. 67 (Me. 1835).
[ii] Hoelmer v. Heiskell, 221 S.W.2d 142 (Mo. 1949).
[iii] Yakima County v. Tullar, 3 Wash. Terr. 393 (Wash. 1888).
[iv] Merrill Stevens Dry Dock Co. v. G & J Invs. Corp., 506 So. 2d 30 (Fla. Dist. Ct. App. 3d Dist. 1987).
[v] Eccles v. Ditto, 23 N.M. 235 (N.M. 1917).
[vi] People v. Thompson, 116 A.D.2d 377 (N.Y. App. Div. 2d Dep’t 1986).
[vii] Maryland Tel. & Tel. Co. v. Ruth, 106 Md. 644 (Md. 1907).