Common law; Intel Corp. v. Hamidi (2003) 30 Cal.4th 1342; CACI No. 2101
Trespass to chattels: the tort that needs actual damage, and what that meant for email
A claim in California superior courts · Last verified August 26, 2026
Trespass to chattels is conversion's smaller sibling. Someone interfered with your personal property, but not seriously enough that they should be made to buy it.
The distinction from conversion is the remedy, and it follows from the severity. Conversion is a forced sale — the defendant pays the property's full value. Trespass to chattels pays only the actual harm: the diminished value, the loss of use, the cost of repair.
And unlike trespass to land, this tort requires actual damage. There are no nominal damages for the bare touching of a chattel. That requirement is the whole of the doctrine, and it is what made this obscure tort briefly important to the internet.
What the claim is
Someone intentionally interfered with your personal property — used it, damaged it, or briefly dispossessed you of it — and you were harmed.
The recurring situations: a vehicle taken and returned damaged; equipment used without permission and worn or broken; property briefly withheld; an animal injured; unauthorised access to a computer system that degrades it.
Where the right comes from
Common law. Intel Corp. v. Hamidi (2003) 30 Cal.4th 1342 is the controlling modern statement.
What a plaintiff has to prove — CACI No. 2101
- The plaintiff owned, possessed, or had a right to possess the personal property.
- The defendant intentionally interfered with the plaintiff's use or possession of it.
- The plaintiff did not consent.
- The plaintiff was harmed.
- The defendant's conduct was a substantial factor in causing the harm.
Element four is not a formality. The interference must have caused actual injury — to the property itself, to its value, or to the plaintiff's legally protected interest in it. A momentary or theoretical deprivation is not enough absent dispossession.
Intent means intending the act, not intending harm. A defendant who used your equipment believing they were entitled to does so intentionally for these purposes.
Hamidi — where the damage requirement did its work
A former Intel employee sent six mass emails to tens of thousands of Intel employees over nearly two years, on the company's own system, ignoring demands to stop. Intel sued for trespass to chattels, arguing the messages consumed its resources and disrupted its workplace.
The Supreme Court held there was no trespass. The emails neither damaged Intel's computer system nor impaired its functioning. The disruption Intel complained of was to its employees and its business, not to the chattel itself — and the tort protects the property, not the owner's peace of mind about what the property is used to say.
The holding is a boundary, not a technicality. Had the tort been extended to unwanted but harmless electronic contact, it would have become a general-purpose remedy against communications the recipient disliked. The Court declined to make it one.
What still qualifies: conduct that measurably degrades a system — consuming bandwidth or storage to the point of impairment, crashing a server, disabling equipment. Automated scraping and bot traffic claims still turn on exactly this question, and the plaintiff who can show measurable degradation has a claim while the one who can show only annoyance does not.
How long you have to file
Three years, under CCP § 338(c), the same subdivision that governs conversion — taking, detaining, or injuring goods or chattels.
The discovery rule applies where the interference was concealed.
Each separate interference is its own claim, so a course of repeated conduct produces a mix of live and time-barred claims rather than one accrual date.
What has to happen before you file
Nothing.
Unless a public entity is a defendant, in which case the Government Claims Act's six-month presentation requirement applies.
Who can be sued — and who can sue
Anyone who interfered intentionally.
A possessory interest is enough to sue — ownership is not required. A bailee, lessee, or lienholder may bring the claim.
Common defenses
No actual damage — the Hamidi defense, and the one that disposes of most modern claims.
Consent, including consent implied by making a system publicly accessible. A website open to the public has, to some degree, invited access, and the scope of that implied consent is the fight in scraping cases.
A superior right of possession, or a privilege such as lawful repossession.
The interference was too trivial to be actionable.
The limitations period.
Anti-SLAPP, where the interference consisted of protected speech or petitioning activity — which was precisely the shape of Hamidi, an employee communicating about workplace conditions.
What the claim pays
Actual damages only, measured by:
- the diminution in value of the property,
- the cost of repair,
- the loss of use during the interference, and
- consequential damages proximately caused.
Not the full value of the property. That is conversion's remedy, and the difference is the point of the distinction. A plaintiff whose property was substantially interfered with should plead conversion, which pays the whole value; one whose property was merely used or briefly withheld gets this.
No nominal damages. Unlike trespass to land, the bare interference is not actionable.
Punitive damages under Civil Code § 3294 on clear and convincing proof of oppression, fraud, or malice.
No fee-shifting.
Jury trial: yes.
What people get wrong
"They touched my property, so I have a claim." Not without actual damage. There are no nominal damages here.
"Unwanted emails are trespassing on my servers." Not after Hamidi, unless they damage or impair the system.
"It's the same as conversion." It is not. Conversion pays the full value of the property because the interference was serious enough to amount to a forced sale. This pays only the harm done.
"I should plead both to be safe." Reasonable — but understand the election: if the interference was substantial, conversion is worth far more, and pleading only trespass to chattels under-values the claim.
"My data was taken, so that's trespass to chattels." Possibly, but a trade secret or statutory computer-access claim usually fits better, and taking data rarely impairs the system it came from.
"I have two years." Three, under § 338(c).
Where it came from
The tort is ancient and was, for most of the twentieth century, close to obsolete. Conversion covered serious interferences; trivial ones were not worth suing over; and the space between them was small enough that the action was mostly a textbook curiosity.
The internet revived it. In the late 1990s, plaintiffs facing unsolicited bulk email, automated data collection, and unwanted server access found no statute that clearly fit and reached for the one tort that reached interference with property without dispossession. A series of decisions allowed those claims, and for a few years trespass to chattels looked as though it might become the general common law of unwanted electronic contact.
Hamidi (2003) stopped that. By holding to the actual-damage requirement, the Supreme Court kept the tort tied to injury to the property rather than to the owner's objection to the contact — and in doing so declined to create, through an old tort, a right to control who may communicate with one's employees.
The requirement it enforced is the same one that always distinguished this tort from trespass to land, and Hamidi is best read not as an internet decision but as a refusal to abandon that distinction under pressure from new facts.
Common questions
How is this different from conversion?
Severity and remedy. Conversion involves interference serious enough that the defendant must pay the property's full value — a forced sale. Trespass to chattels covers lesser interferences and pays only the actual harm: repair cost, lost value, loss of use.
Do I have to prove damage?
Yes. Unlike trespass to land, there are no nominal damages. Without actual injury to the property or your interest in it, there is no claim.
Are unwanted emails a trespass to my system?
Not under Intel Corp. v. Hamidi, unless they damage the system or impair its functioning. Disruption to your business or your people is not injury to the chattel.
What about bots scraping my website?
It depends on measurable impairment. A plaintiff who can show the traffic degraded the system has a claim; one who objects to the access itself generally does not.
How long do I have to sue?
Three years, under CCP § 338(c) — the same subdivision as conversion.
Should I plead conversion instead?
If the interference was substantial, yes — it pays far more. Many plaintiffs plead both and let the evidence determine which fits.