Negligent security glossaryThe words in your case, in plain English.

Our negligent security guides use these words because the statutes, the jury instructions and the court decisions do. Each definition names its source and was checked on November 11, 2026. The decisions themselves are explained one paragraph each on California negligent security cases, and our guide on how to prove a negligent security case shows how the terms fit together.

The basic rule

California's jury instruction on crime on property, CACI No. 1005 (2026 edition), says that a landlord or the owner of a business open to the public "must use reasonable care to protect" tenants, guests or patrons "from another person's criminal conduct on" the property "if the [owner/landlord] can reasonably anticipate that conduct." Whether that duty exists is decided by the judge; whether the steps the owner took were "adequate and reasonable under the circumstances" is decided by the jury. Injuries from unsafe conditions rather than crime are covered on our premises liability page.

Related guides

• Los Angeles negligent security lawyer: where to start
• When the attacker is mostly at fault: Proposition 51 and the attacker's share
• Negligent security deadlines: the time limits, with the sexual assault windows
• Negligent security evidence checklist: the records to keep and request, by county
• Deadline calculator: a first look at the dates

Sources cited

• Judicial Council of California Civil Jury Instructions (2026 edition), CACI Nos. 406, 450C, 1000, 1005, 1006 and 1011: courts.ca.gov
• Civil Code, california.public.law: sections 1431.2, 1714, 1941.5 and 3294
• Code of Civil Procedure, california.public.law: sections 335.1, 340.16 and 527.6
• Government Code, california.public.law: sections 911.2 and 7923.615
• Evidence Code section 413, california.public.law: section 413
• Business and Professions Code, california.public.law: sections 7583.39 and 7583.40
• California Supreme Court decisions, CourtListener: Ann M. v. Pacific Plaza Shopping Center (1993) 6 Cal.4th 666, Delgado v. Trax Bar & Grill (2005) 36 Cal.4th 224, Morris v. De La Torre (2005) 36 Cal.4th 260, Castaneda v. Olsher (2007) 41 Cal.4th 1205, Frances T. v. Village Green Owners Assn. (1986) 42 Cal.3d 490, Brown v. USA Taekwondo (2021) 11 Cal.5th 204, Saelzler v. Advanced Group 400 (2001) 25 Cal.4th 763 and B.B. v. County of Los Angeles (2020) 10 Cal.5th 1
• Court of Appeal decisions, CourtListener: Vasquez v. Residential Investments, Inc. (2004) 118 Cal.App.4th 269, Madhani v. Cooper (2003) 106 Cal.App.4th 412, Weidenfeller v. Star & Garter (1991) 1 Cal.App.4th 1, Century Transit Systems, Inc. v. American Empire Surplus Lines Insurance Co. (1996) 42 Cal.App.4th 121 and State Farm Fire & Casualty Co. v. Elizabeth N. (1992) 9 Cal.App.4th 1232
• PPG Industries, Inc. v. Transamerica Insurance Co. (1999) 20 Cal.4th 310: SCOCAL, Stanford Law School
• California Victim Compensation Board: who is eligible, what is covered and repayment

Glossary terms

The terms run in the order a claim usually meets them: who owes a duty, what the owner knew, how the claim is proved, the security company, how fault is shared, who pays, and the deadlines and help available. Each term has its own link, so one definition can be shared.

Negligent security

A claim that an owner, landlord or business failed to take reasonable steps against a crime it could anticipate. California's jury instruction, CACI No. 1005 (2026 edition), says a landlord or the owner of a business open to the public "must use reasonable care to protect" tenants, guests or patrons "from another person's criminal conduct on" the property "if the [owner/landlord] can reasonably anticipate that conduct."

Duty of care

The legal obligation to use reasonable care toward others, rooted in Civil Code section 1714(a). In a negligent security case, the judge decides whether the owner owed a duty to protect against crime, and the jury decides whether its steps were "adequate and reasonable under the circumstances" (CACI No. 1005).

Special relationship

A relationship that gives one party a legal duty to protect another from third persons, such as landlord and tenant, business and patron, or innkeeper and guest. The California Supreme Court treats it, or another basis for "an affirmative duty to protect," as the first step in deciding whether such a duty exists (Brown v. USA Taekwondo (2021)).

Business proprietor

The owner or operator of a business open to the public, such as a store, restaurant, bar or hotel. A proprietor with actual notice of an impending assault must take "reasonable, relatively simple, and minimally burdensome steps to attempt to avert that danger" (Delgado v. Trax Bar & Grill (2005)), which as a general matter include calling 911 (Morris v. De La Torre (2005)).

Innkeeper

The traditional legal word for a hotel or motel operator. California courts have said "an innkeeper was under a duty to protect his guests" at a time when landlords traditionally had no such duty (O'Hara v. Western Seven Trees Corp. (1977), as quoted in Frances T. v. Village Green Owners Assn. (1986)). Today that is a duty of reasonable care against foreseeable crime, not a guarantee of safety.

Common area

A part of a property the landlord or owner keeps under its own control for shared use, "such as common hallways, stairs, elevators, or roof" (Uccello v. Laudenslayer (1975), as quoted in CACI No. 1006). A landlord owes tenants a duty "to take reasonable steps to secure the common areas under its control" (Ann M. v. Pacific Plaza Shopping Center (1993), as quoted in CACI No. 1006).

Foreseeability

Whether the owner could reasonably anticipate the kind of crime that happened. "Foreseeability, when analyzed to determine the existence or scope of a duty, is a question of law to be decided by the court" (Ann M. v. Pacific Plaza Shopping Center (1993)). Courts weigh it against the burden of the missing security measure.

Sliding scale

The balancing test courts use to decide what security an owner owed. "The more certain the likelihood of harm, the higher the burden a court will impose on a landlord to prevent it; the less foreseeable the harm, the lower the burden a court will place on a landlord" (Castaneda v. Olsher (2007), quoting Vasquez v. Residential Investments, Inc. (2004)).

Heightened foreseeability

The level of foreseeability required before an owner must provide costly measures such as guards, "shown by prior similar incidents or other indications of a reasonably foreseeable risk of violent criminal assaults in that location" (Delgado v. Trax Bar & Grill (2005), as quoted in CACI No. 1005). Without it, a business may still owe simple responses to an attack its staff can see.

Prior similar incidents

Earlier crimes on the same property that resemble the one that happened. The foreseeability needed to require guards "rarely, if ever, can be proven in the absence of prior similar incidents of violent crime on the landowner's premises" (Ann M. v. Pacific Plaza Shopping Center (1993)). Crimes at an immediately neighboring, similar business can help show foreseeability (Castaneda v. Olsher (2007)).

Notice

What the owner, landlord or manager was told or knew before the attack, such as written complaints, police calls or a protective order handed to the manager. California cases treat reports made to a property manager as notice to the landlord (Castaneda v. Olsher (2007); Madhani v. Cooper (2003)). The strongest cases usually involve written reports to the landlord or manager about threats or violence by a specific person, and no meaningful response.

Constructive notice

Knowledge the law charges to someone who should have discovered a condition, even if no one reported it; California's jury instructions use it for physical conditions on property (CACI No. 1011). For crime by a third person, a Court of Appeal has said foreseeability "is tested by what the defendant knows, not what the defendant could have or should have learned" (Margaret W. v. Kelley R. (2006), as quoted in CACI No. 1005).

Causation

The link between the owner's failure and the injury. The injured person must show, "by nonspeculative evidence, some actual causal link" between the injury and the missing security (Saelzler v. Advanced Group 400 (2001)), usually that the measure more likely than not would have prevented the attack or reduced the harm.

Substantial factor

The causation standard in California's jury instructions: the owner's negligence must have been a "substantial factor" in causing the harm (CACI No. 1000). In Castaneda v. Olsher (2007), a lighting claim failed because the plaintiff "simply has not shown that the absence of brighter lights was likely a substantial factor."

Negligent undertaking

The rule that a company that agrees to provide protective services, such as a security company hired to guard a building, can be liable for providing them carelessly (CACI No. 450C). The theory "is typically applied where the defendant has contractually agreed to provide services for the protection of others, but has negligently done so" (Lichtman v. Siemens Industry Inc. (2017), as quoted in CACI No. 450C).

Post orders

The written instructions a security company gives its guards for one site, such as where to stand, what to patrol and whom to keep out. With the contract, patrol logs and incident reports, post orders show what the company agreed to do, which is the measure of its duty. We found no statute that sets how long they must be kept, so they belong in an early preservation letter.

Private patrol operator

California's licensing term for a security guard company. It must keep liability insurance of at least "one million dollars ($1,000,000) for any one loss or occurrence" (Business and Professions Code section 7583.40), or its license is suspended automatically (section 7583.39(b)).

Comparative fault

California's system for dividing responsibility for an injury among everyone whose fault contributed to it, which in a crime case can include the attacker, the owner and sometimes the injured person. In Weidenfeller v. Star & Garter (1991), a jury assigned 75 percent of the fault to the assailant, 20 percent to the bar and 5 percent to the patron who was hurt.

Proposition 51

The voter-approved rule in Civil Code section 1431.2 that each defendant's liability for noneconomic damages "shall be several only and shall not be joint." Each defendant pays only its own share of noneconomic damages, such as pain and emotional distress, but economic damages, such as medical bills and lost earnings, are not divided this way. An attacker cannot use the rule to reduce its own share because others were negligent (B.B. v. County of Los Angeles (2020)).

Several liability

Liability for only one's own share of a loss. An owner pays all the economic damages it is liable for, but only its own percentage of noneconomic damages (Civil Code section 1431.2). In Weidenfeller v. Star & Garter (1991), a bar found 20 percent at fault paid $50,000 of $250,000 in noneconomic damages.

Nonparty fault

Fault a jury assigns to someone who is not a defendant, such as an attacker who was never caught or sued. A defendant's share is measured against "all fault responsible for the plaintiff's injuries, not merely that of 'defendant[s]' present in the lawsuit" (DaFonte v. Up-Right, Inc. (1992), as quoted in CACI No. 406), and the defendant must offer evidence of the nonparty's fault.

Policy limits

The most a liability insurance policy will pay, usually for each occurrence. Several injured people may share one limit (State Farm Fire & Casualty Co. v. Elizabeth N. (1992)), and an insurer that unreasonably refuses a reasonable offer within the limits can become responsible for more (PPG Industries, Inc. v. Transamerica Insurance Co. (1999)).

Assault and battery exclusion

Some liability policies exclude claims based on an assault or battery, and some limit them to a smaller amount. A California Court of Appeal held that such an exclusion applied "no matter who commits" the assault and whatever legal theory the injured person uses (Century Transit Systems, Inc. v. American Empire Surplus Lines Insurance Co. (1996) 42 Cal.App.4th 121). Identifying every policy, including policies held by a security company or a management company, is part of the early work in these cases.

Umbrella policy

An insurance policy that pays above a primary liability policy once the primary limit is used up. Umbrella and excess policies generally follow the primary policy's terms and may add exclusions of their own, so each layer's declarations page and endorsements must be read.

Punitive damages

Damages meant to punish, not to compensate. Punitive damages require clear and convincing evidence of oppression, fraud or malice (Civil Code section 3294), and against a company the conduct must involve an officer, director or managing agent. The California Supreme Court has said that public policy prohibits insurance from paying punitive damages (PPG Industries, Inc. v. Transamerica Insurance Co. (1999) 20 Cal.4th 310).

Preservation letter

A written demand, sent early, asking the owner, manager, security company and others to keep evidence and turn off automatic deletion. We found no California statute that makes a private owner keep camera footage for a set time, so the letter is what tells the owner the material is evidence. If it is then destroyed, a jury may consider "willful suppression of evidence" (Evidence Code section 413).

Calls for service

The record of calls to police at an address. Police agencies must make public "the time, substance, and location of all complaints or requests for assistance received by the agency and the time and nature of the response thereto," with safety and investigation exceptions (Government Code section 7923.615). The Los Angeles Police Department's public data has no address column, so a building's history comes by records request or subpoena.

Protective order

A court order that tells a person to stay away from someone or stop harassing them (Code of Civil Procedure section 527.6). When the person accused of abuse or violence does not live in the tenant's unit, the landlord must change the locks within 24 hours after the tenant asks in writing and gives it a copy (Civil Code section 1941.5). If the landlord received a copy of a protective order, that is strong evidence of what it knew.

Statute of limitations

The deadline to file a lawsuit. Most California injury lawsuits must be filed within two years of the injury (Code of Civil Procedure section 335.1). Some claims have more time, including claims arising from a sexual assault on an adult (section 340.16), and the dates in any one case should be calculated by a lawyer.

Revival window

A period during which a statute lets a claim be filed after the time limit had run out. Code of Civil Procedure section 340.16(b)(3) revived adult sexual assault claims for conduct on or after January 1, 2009, and they "may be commenced until December 31, 2026," as of November 11, 2026, the date this page was checked. A second window, in section 340.16(e), runs from January 1, 2026 through December 31, 2027, and whether a claim qualifies under either window is a question for a lawyer.

Cover up

In Code of Civil Procedure section 340.16(e), "a concerted effort to hide evidence relating to a sexual assault that incentivizes individuals to remain silent or prevents information relating to a sexual assault from becoming public or being disclosed to the plaintiff," including through nondisclosure or confidentiality agreements. That definition controls the second revival window: section 340.16(e) revives adult sexual assault claims against a private entity alleged to have covered up, or tried to cover up, an earlier assault or allegation by the same perpetrator, from January 1, 2026 through December 31, 2027 (checked November 11, 2026). The second window does not revive a claim against a public entity (section 340.16(e)(7)(C)), and a claim against a public entity also requires a written government claim, generally within six months (Government Code section 911.2).

CalVCB

The California Victim Compensation Board, which can pay up to $70,000 toward medical, counseling, lost income, relocation and home security costs after crimes such as assault, robbery, sexual assault and stalking, but not pain and suffering. Victims generally apply within seven years; CalVCB is a "payor of last resort," must be repaid from a later recovery for the same expenses, and must be told of a lawsuit within 30 days of filing.