Negligence begins with a duty of reasonable care
California Civil Code § 1714 states a broad ordinary-care principle, subject to statutory qualifications. In practical terms, your claim usually begins by asking whether a person or organization had a legal duty to act with reasonable care toward you. The answer depends on the relationship, activity, control, foreseeability of harm, and any statutes or public policies that shape the duty.
A duty does not require someone to prevent every possible injury. The law asks what care was reasonable under the actual circumstances. A business, service provider, organizer, supervisor, property controller, product company, contractor, or individual may have different obligations. If a focused category such as unsafe property, defective products, medical care, workplace third-party injury, or public entity applies, that more specific framework may control.
Breach and causation must be connected
After identifying a duty, you generally must show how the defendant failed to meet it. A rule violation, ignored warning, unsafe method, lack of supervision, or unreasonable decision may be relevant. The claim should explain what a reasonably careful person or organization would have done differently, not simply state that the result was harmful.
You also must connect that failure to your physical injury. Conduct can be careless without causing the event, and an injury can occur without resulting from the alleged failure. When you had a prior condition, the issue may be whether the event caused a new injury or aggravated the earlier one. Medical and factual causation should be evaluated separately from blame.
Responsibility can extend through relationships
The person who acted may not be the only potential defendant. A vehicle or property owner, employer, principal, contractor, business operator, or product company may have responsibility when California law and the facts support the relationship. The existence of a contract, uniform, logo, or business connection is a starting point, not proof that every related entity is legally responsible.
If several people contributed, comparative fault can allocate responsibility. Civil Code § 1431.2 makes noneconomic-damage responsibility several and proportionate to each defendant's percentage of fault in comparative-fault actions, while economic-damage rules can differ. Your own conduct may also be considered, but partial fault does not automatically eliminate a bodily injury claim.
The correct category determines the deadline
Code of Civil Procedure § 335.1 generally provides two years for many actions involving injury or death caused by wrongful act or neglect, subject to exceptions. That period is not universal. A public-entity claim generally requires presentation within six months. Medical professional negligence, hazardous exposure, claims involving minors, and other specialized matters may use different accrual or filing rules.
Insurance notice provisions, contractual requirements, and the identity of an unknown defendant can add separate issues. You do not need to know the final legal label before asking for a review, but the category should be identified early enough to protect the shortest possible deadline. An insurer's investigation or settlement discussion does not necessarily pause the time to act.