Manufacturing, Design or Warning Defect?

The first question in most defective product cases is not who to blame but what went wrong with the product. California's civil jury instructions, written by the Judicial Council, sort product defects into three types, and each type has its own list of facts a jury must find. Knowing which type fits your injury shapes what evidence matters, which experts may be needed and which companies can be named.

This guide walks through the three types, the tests a jury uses for each, the defenses manufacturers raise, and what to do with the product itself while the questions are sorted out.

How do I work out which kind of defect I have, step by step?

Keep the product exactly as it is. Do not repair it, throw it away or send it back to the company. A manufacturing defect is shown by comparing your unit with the design and with other units, which is impossible without the unit.
Ask whether your unit is different. If a part is missing, cracked, contaminated or assembled wrong compared with identical products, that points to a manufacturing defect (CACI 1202).
Ask whether every unit is built the same risky way. If the danger comes from how the product was planned, such as a missing guard or a weak latch on every unit, that points to a design defect (CACI 1203 and 1204).
Read the label, manual and packaging. If the product carried a hidden risk that a warning or clear instructions would have avoided, that points to a warning defect (CACI 1205).
Write down how you were using it. Each test turns on use in an intended or reasonably foreseeable way, so details of the use matter from the start.
List everyone who made, distributed or sold it. Strict liability can reach more than the brand on the label; our guide on suing the store or seller that sold a defective product explains who is in the chain.
Find your deadline. Most product injury lawsuits must be filed within two years (Code of Civil Procedure 335.1), with special rules for injuries that appear later.

How do the three kinds of defect compare?

Kind of defect	What it means	What the jury decides	Instruction
Manufacturing defect	The product differs from the manufacturer's design or specifications, or from other typical units of the same product line	Whether the defect existed when the product left the defendant's possession and was a substantial factor in causing harm	CACI 1201 and 1202
Design defect: consumer expectation test	The product did not perform as safely as an ordinary consumer would expect when used or misused in an intended or reasonably foreseeable way	Whether that failure to perform safely was a substantial factor in causing harm	CACI 1203
Design defect: risk-benefit test	The design caused harm, and the company cannot prove the design's benefits outweigh its risks	Gravity and likelihood of harm, feasibility, cost and disadvantages of a safer alternative design	CACI 1204
Failure to warn	A known or knowable risk that ordinary consumers would not recognize was not adequately warned of or explained	Whether the lack of sufficient instructions or warnings was a substantial factor in causing harm	CACI 1205

What counts as a manufacturing defect?

A product has a manufacturing defect if it differs from the manufacturer's design or specifications, or from other typical units of the same product line (CACI 1202). Think of a ladder whose rivet was never set, a tire with a flaw in one batch, or a medication contaminated at the plant. The design may be perfectly safe; the problem is that your unit did not match it.

To win this claim, the injured person must prove four things: that the defendant made, distributed or sold the product, that the defect was present when the product left that defendant's possession, that the person was harmed, and that the defect was a substantial factor in causing the harm (CACI 1201). A decision the Judicial Council quotes under CACI 1201 says that proof the product malfunctioned is essential to establish liability for an injury caused by the defect. That is why the physical product, and records of how it failed, carry so much weight.

How is a design defect proven?

California gives an injured person two separate ways to prove a design defect, and both may be presented in the same case (Directions for Use, CACI 1203).

The consumer expectation test asks whether the product failed to perform as safely as an ordinary consumer would expect when used or misused in an intended or reasonably foreseeable way (CACI 1203). Decisions the Judicial Council quotes under CACI 1203 say it measures the expectations of a hypothetical reasonable consumer, not the particular person who was hurt. Another decision the Judicial Council quotes under CACI 1203 says this test is reserved for cases where the everyday experience of the product's users permits a conclusion that the design violated minimum safety assumptions. For a complex product whose failure ordinary users cannot judge from experience, the court may decide this test does not fit.

The risk-benefit test shifts the burden. The injured person proves that the defendant made, distributed or sold the product, that they were harmed, and that the design was a substantial factor in the harm. The jury must then find for the injured person unless the company proves that the benefits of the design outweigh its risks (CACI 1204). The jury weighs how serious the potential harm is, how likely it is, whether a safer alternative design was feasible when the product was made, what that alternative would cost, and its disadvantages.

The two tests are alternatives, not defenses to each other. According to a decision the Judicial Council quotes under CACI 1203, a product can be defective under the consumer expectation test even if the design's benefits outweigh its risks. Evidence of what other manufacturers did can come in under the risk-benefit test in some cases, but the Judicial Council's notes to CACI 1204 say the opposing party can ask for an instruction limiting how the jury uses it.

When is a missing or weak warning a defect?

A product made exactly as designed can still be defective if it reaches the user without the instructions or warnings needed to use it safely. Under CACI 1205, the injured person must show that the product had potential risks that were known or knowable in light of the scientific knowledge generally accepted at the time of manufacture, distribution or sale; that the risks presented a substantial danger when the product was used or misused in an intended or reasonably foreseeable way; that ordinary consumers would not have recognized them; that the defendant failed to warn or instruct adequately; and that the missing warning was a substantial factor in causing the harm.

Several limits apply. A decision quoted under CACI 1205 says there is no duty to warn of known risks or obvious dangers. For prescription drugs and implants, the warning goes to the prescribing physician rather than the patient, and the manufacturer has a continuing duty to warn physicians while the product is in use (CACI 1205). A company may also argue that the injured person was a sophisticated user who, because of training or experience, knew or should have known of the danger (CACI 1244). That defense can matter for tools and equipment used by trained workers; our guide on injuries from a defective machine at work covers that setting.

Do I have to prove the company was careless?

Not for the three strict liability claims above. The instructions for manufacturing defect, design defect and failure to warn do not ask whether the company acted reasonably. A decision quoted under CACI 1200 explains the purpose: the costs of injuries from defective products should be borne by the manufacturers that put them on the market, rather than by injured people who cannot protect themselves. Strict liability is still not automatic; another decision quoted there says the manufacturer does not become the insurer of the user's safety. A defect, harm and causation must all be proven.

A claim can also be brought in negligence alongside strict liability. The Judicial Council has separate instructions for negligent design or manufacture (CACI 1220), negligent failure to warn (CACI 1222) and negligent failure to recall or retrofit a product after learning of a danger (CACI 1223). Negligence can matter where strict liability does not reach, for example against a company that installed, inspected or repaired a product (CACI 1220). If the evidence shows the company knew of the danger and chose to ignore it, read our guide on punitive damages against a manufacturer.

What changes the answer?

The company says you misused or changed the product. Misuse or modification is a complete defense only if it was so highly extraordinary that it was not reasonably foreseeable and was the sole cause of the harm (CACI 1245). If it was only one cause among others, it may reduce your recovery by your share of fault instead of ending the claim (CACI 1207A).

You were a bystander, not the buyer or user. A decision quoted under CACI 1200 says bystanders should be entitled to greater protection than the consumer or user where injury to them is reasonably foreseeable, because they have no chance to inspect the product or choose a reputable seller.

The defect was in a component. A component maker is generally not liable for a defect in the finished product, unless its component itself was defective or it substantially participated in integrating the component into a design that turned out defective (CACI 1208).

The product is an inherently unsafe everyday product. A manufacturer or seller is not liable when a common consumer product intended for personal consumption, such as sugar or alcohol, is inherently unsafe and known to be unsafe by ordinary consumers (Civil Code 1714.45). That rule does not apply to a manufacturing defect claim.

The injury came from exposure and appeared years later. Exposure to a hazardous material or toxic substance has its own discovery-based deadline (Code of Civil Procedure 340.8). Our guide on when the deadline starts for a product injury that shows up later explains how the clock runs.

The product was a vehicle or vehicle part. The same three tests apply, but a crash often involves a driver's fault too; see whether a defective car part can be the cause of a crash claim.

What could this look like? An example

For example, imagine a Rohnert Park parent who buys an electric pressure cooker from a large retailer. A few months later, the lid opens while the pot is still under pressure, and boiling liquid burns the parent's arm. The parent keeps the cooker, the box and the manual, and photographs the burns.

An engineer's inspection could point in several directions. If a locking pin on this one unit was never installed, the claim looks like a manufacturing defect, because the unit differs from the design. If every unit's lock can be defeated by normal twisting, the claim looks like a design defect, judged by what an ordinary cook would expect and by whether a safer lock was feasible. If the manual never warned that the lid can be forced open under pressure, a warning claim may be added. The retailer, the distributor and the manufacturer could all be named, and the lawsuit would be filed within two years of the burn. This example is made up to show how the rules fit together; it says nothing about any real case.

What mistakes do people make with product injuries?

Throwing the product away, returning it for a refund, or letting a repair shop fix it before anyone inspects it.
Assuming they must prove the company was careless, when the strict liability claims do not require it.
Choosing only one theory, when manufacturing, design and warning claims can all be raised together.
Assuming there is no claim because the product was never recalled; none of the strict liability instructions lists a recall as an element.
Waiting too long while the company "looks into it," as the two-year deadline keeps running.

What should I do this week?

Put the product, its parts, packaging, manual and receipt in a safe place where no one will alter them.
Photograph the product from every side, and your injuries as they change.
Write down how you were using the product, step by step, and who saw it happen.
Note the brand, model, serial or lot number and where you bought it.
Keep every medical record and bill; our guide on what to bring to a first meeting with an injury lawyer lists the papers that help.
Do not sign anything from the manufacturer or its insurer, and do not hand over the product, without advice.
Read our guide to California personal injury deadlines and mark the date on a calendar.

Frequently asked questions

Can one product have more than one kind of defect?

Yes. The Judicial Council's general product instruction lists all three, a manufacturing defect, a defective design and insufficient instructions or warnings, as alternatives that can be claimed together (CACI 1200).

Who decides whether the consumer expectation test applies?

The judge first decides whether the product is one about which ordinary consumers can form minimum safety expectations, and in some cases leaves that question to the jury (Directions for Use, CACI 1203). If the test does not fit, the case proceeds under the risk-benefit test.

Does the company have to prove its design was safe?

Under the risk-benefit test, yes. Once the injured person shows the design was a substantial factor in causing harm, the company must prove the benefits of its design outweigh the risks (CACI 1204).

What if the warning was there but in small print?

The question is whether the company adequately warned or instructed. A decision the Judicial Council quotes under CACI 1205 says the adequacy of a warning is in most cases a question of fact for the jury.

Does it matter that I was partly careless?

It can reduce your recovery by your percentage of responsibility, but it does not by itself bar the claim (CACI 1207A). Only unforeseeable misuse that was the sole cause of the harm is a complete defense (CACI 1245).

Where would a product lawsuit be filed here?

An injury lawsuit may be filed in the county where the injury happened or where a defendant lives (Code of Civil Procedure 395), so an injury here can be filed in Sonoma County Superior Court even when the manufacturer is based elsewhere. Our page on what to expect at Sonoma County Superior Court covers filing and the stages that follow.

What can I recover in a product case?

The same damages as in other injury cases, such as medical expenses, lost earnings and pain and suffering. Our guide on how pain and suffering is valued in California explains the noneconomic part.

If a product injured you or someone in your family, contact Young Law Group today at (707) 343-0556 or through our contact page for a free consultation about what went wrong and who may be responsible.

Manufacturing defect, design defect, or failure to warn: which kind of product case do I have?