The failure to use reasonable care. The doing of something which a reasonably prudent person would not do, or the failure to do something which a reasonably prudent person would do under like circumstances. A departure from what an ordinary reasonable member of the community would do in the same community.
Negligence is a 'legal cause' of damage if it directly and in natural and continuous sequence produces or contributes substantially to producing such damage, so it can reasonably be said that if not for the negligence, the loss, injury or damage would not have occurred.
Negligence may be a legal cause of damage even though it operates in combination with the act of another, a natural cause, or some other cause if the other cause occurs at the same time as the negligence and if the negligence contributes substantially to producing such damage.
In cases involving allegedly defective, unreasonably dangerous products, the manufacturer may be liable even though it exercised all reasonable care in the design, manufacture and sale of the product in question.
On the other hand, any failure of a manufacturer of a product to adopt the most modern, or even a better safeguard, does not necessarily make the manufacturer legally liable to a person injured by that product. The manufacturer is not a guarantor that nobody will get hurt in using its product, and a product is not defective or unreasonably dangerous merely because it is possible to be injured while using it. There is no duty upon the manufacturer to produce a product that is 'accident-proof.' What the manufacturer is required to do is to make a product which is free from defective and unreasonably dangerous conditions.
In general, the law of California declares that '[e]very one is responsible . . . for an injury occasioned to another by his want of ordinary care or skill in the management of his property or person . . . .' Cal.Civ.Code Sec. 1714(a). That, of course, means that people are generally liable when they negligently injure others. If the language is a bit quaint, it is because that has been the law of California since at least 1872. The California courts have assiduously enforced that principle and only deviate from it when some powerful public policy dictates a contrary result. See Lipson v. Superior Court, 31 Cal. 3d 362, 372-73 (1982).
When considered in relation to contracts, negligence may be divided into various degrees:
Ordinary negligence is the want of ordinary diligence; Slight or less than ordinary negligence is the want of great diligence; Gross or more than ordinary negligence is the want of slight diligence.
Three great principles of responsibility seem naturally to follow this division.
In those contracts which are made for the sole benefit of the creditor, the debtor is responsible only for gross negligence, good faith alone being required of him, as in the case of a depositary who is a bailee without reward.
In those contracts which are for the reciprocal benefit of both parties such as those of sale, of hiring, of pledge and the like, the party is bound to take that care which a prudent man ordinarily takes of his affairs and he will therefore be held responsible for ordinary neglect.
In those contracts made for the sole interest of the party who has received and is to return the thing which is the object of the contract, e.g., a loan for a thing's use, the slightest negligence will make him responsible.
In general, a party who has caused an injury or loss to another in consequence of his negligence is responsible for all the consequences. An example of this may be found in the case of a person who drives a car during a dark night on the wrong side of the road and injures another.
When the law imposes a duty on an officer, whether by common law or statute, and he neglects to perform it, he may be held accountable for such neglect and in some cases such neglect will amount to a forfeiture of the office.