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Practice Tip: Check for the Sophisticated User

By Kimberly H. Clancy
August 31, 2006

As with many things in law, there is a mental checklist. When a client calls seeking advice regarding a new product liability lawsuit, you run through the product liability checklist. What is the product? What is the product used for? What warnings accompanied the product? When was the product manufactured? How did the product allegedly cause injury?

Before finishing the checklist, don't get forget to also ask your client about the user of the product. Did the user have experience with the product? Was the user independently aware of dangers associated with the product? A recent California Court of Appeal case reminds us that the answers to those questions may indicate that your client has a 'sophisticated user' defense.

In Johnson v. American Standard, Inc., 34 Cal. Rptr. 3d 863 (Cal. Ct. App. 2005) (review granted), the California Court of Appeal upheld summary judgment for the manufacturer of air conditioning equipment based on the 'sophisticated user' defense. At issue in Johnson was whether the defendant manufacturer of air conditioning equipment had a duty to warn the plaintiff, an air conditioning repairman, about the dangers of brazing refrigerant lines. Brazing, or welding, refrigerant lines can create phosgene gas, the inhalation of which can result in potentially fatal lung disease. Phosgene gas can be detected three ways: 1) through its fresh-cut grass smell; 2) through changes in flame color during brazing; or 3) through physical symptoms like burning eyes and shortness of breath.

The plaintiff in Johnson was an experienced HVAC (heating, ventilation, and air conditioning) technician. Under federal law, HVAC technicians that work on commercial equipment must be certified by the EPA. The plaintiff had this certification, 1 year of study in HVAC systems at ITT Technical Institute, and several years of on-the-job training and experience. The plaintiff claimed that he was injured while brazing refrigerant lines due to exposure to phosgene gas. His lawsuit claimed that the defendant manufacturer failed to provide an adequate warning that brazing refrigerant lines could result in the creation of phosgene gas.

Evidence presented by the defendant manufacturer showed that experienced HVAC technicians know that brazing refrigerant lines can create phosgene gas. Indications that phosgene gas is present ' the fresh-cut grass smell, the green brazing flame, the physical symptoms ' are well known in the industry. A study guide for EPA certification warns of the dangers of brazing refrigerant lines and the creation of phosgene gas. The Material Safety Data Sheet ('MSDS') for the refrigerant used by the plaintiff warned that heating the refrigerant can release toxic gases.

Based on that evidence, the Johnson court found that the defendant manufacturer did not have a duty to warn the plaintiff that brazing refrigerant lines could create phosgene gas and cause injury because the manufacturer could reasonably expect that HVAC technicians would know of the risk. The foundation for this finding is the sophisticated user defense. The sophisticated user defense holds that 'there is ordinarily no duty to give warnings to members of a profession against generally known risks. There need be no warning to one in a particular trade or profession against a danger generally known to that trade or profession.'

Courts that have adopted the sophisticated user defense often cite to the Restatement Second of Torts '388. Under that provision, the suppliers of chattels can be liable to users of those chattels 'if the supplier (a) knows or has reason to know that the chattel is or is likely to be dangerous for the use for which it is supplied, and (b) has no reason to believe that those for whose use the chattel is supplied will realize its dangerous condition.' Comment k to Clause (b) explains: 'One who supplies a chattel to others to use for any purpose is under a duty to exercise reasonable care to inform them of its dangerous character … if, but only if, he has no reason to expect that those for whose use the chattel is supplied will discover its condition and realize the danger involved.' According to the Johnson court, Clause (b) 'has been interpreted to mean that there is no duty to warn if the user knows or should know of the potential danger, especially where the user is a professional who should be aware of the characteristics of the product.'

The Johnson opinion is a good primer on the sophisticated user defense; it provides several string citations that collect a number of cases, both pre and post-Restatement, that have addressed the defense, its origins, and its variations, over the years. Here is a sampling of those cases and their holdings:

  • Littlehale v. E. I. du Pont de Nemours & Co., 268 F. Supp. 971 (S.D.N.Y. 1966) (product at issue ' blasting caps): 'Moreover, there is ordinarily no duty to give warning to members of a profession against generally known risks. 'There need be no warning to one in a particular trade or profession against a danger known to that trade or profession.”
  • Crook v. Kaneb Pipe Line Operating Partnership, 231 F.3d 1098 (8th Cir. 2000) (product at issue ' propane gas): '[T]he decedent, [his coworker and his employer] were experienced professionals in dealing with propane. This rule of the 'sophisticated user' is no more than an expression of common sense as to why a party should not be liable when no warnings or inadequate warnings are given to one who already knows or could reasonably have been expected to know of the dangers of propane.'
  • Parker v. State, 105 N.Y.S.2d 735, 741 (1951) (product at issue ' blood plasma): 'There is a manifest distinction between selling a medical preparation to the public, who may have no knowledge of the dangers attendant upon its use, and making available a preparation to a hospital at its request, whose physicians may be expected to have knowledge of the dangers involved in utilizing the therapeutic preparation ordered by them. Ordinarily, there is no duty to give warning to the members of a profession against generally known risks.'
  • Thibodaux v. McWane Cast Iron Pipe Co., 381 F.2d 491, 495 (5th Cir. 1967) (product at issue ' cast iron pipe): '[T]he consulting engineers were familiar with or chargeable with the knowledge of the corrosion characteristics of [the manufacturer's] pipe and that such facts were properly within the scope of their own responsibility and expertise. We therefore conclude that [the manufacturer] was under no obligation to inform them of such … '
  • Akin v. Ashland Chemical Co., 156 F.3d 1030, 1037 (10th Cir. 1998) (product at issue ' chemical solvents): '[T]here is no duty to warn members of a profession against dangers generally known to members of that profession … Because of the wealth of research available, the ability of the Air Force to conduct studies, and its extremely knowledgeable staff, we find that the Air Force easily qualifies as a 'knowledgeable purchaser' that should have known the risks involved with low-level chemical exposure. Employees of the Air Force are also deemed to possess the necessary level of sophistication, so that defendants had no duty to warn the Air Force or its employees of the potential hazards.'
  • Billiar v. Minnesota Mining & Manufacturing Co., 623 F.2d 240, 243 (2nd Cir. 1980) (product at issue ' electrical resin): 'When the user is fully aware of the nature of the product and its dangers, however, the supplier cannot be held liable for failure to warn them … The rationale behind the 'knowledgeable user' exception is that knowledge of the danger is equivalent to prior notice; no one needs notice of that which he already knows.'
  • Hall v. Ashland Oil Co., 625 F. Supp. 1515, 1520 (D. Conn. 1986) (product at issue ' benzene): 'In tort law, one with a duty to warn is not liable for failing to warn a party of facts that the party already knew … The theory of this exception is that a failure to warn a party of a danger of which it was independently aware cannot be the proximate cause of injury resulting from that danger, since presumably the party would not have acted differently even if warned.'

As the Johnson opinion and the above summaries highlight, the application of the sophisticated user defense can be broad-ranging, across a number of different products and a number of different professions. So the next time a client calls with a new product liability case, don't forget to check the sophisticated user defense.


Kimberly H. Clancy is an associate at the Los Angeles office of Sidley Austin LLP. She practices in the firm's products liability group.

As with many things in law, there is a mental checklist. When a client calls seeking advice regarding a new product liability lawsuit, you run through the product liability checklist. What is the product? What is the product used for? What warnings accompanied the product? When was the product manufactured? How did the product allegedly cause injury?

Before finishing the checklist, don't get forget to also ask your client about the user of the product. Did the user have experience with the product? Was the user independently aware of dangers associated with the product? A recent California Court of Appeal case reminds us that the answers to those questions may indicate that your client has a 'sophisticated user' defense.

In Johnson v. American Standard, Inc., 34 Cal. Rptr. 3d 863 (Cal. Ct. App. 2005) (review granted), the California Court of Appeal upheld summary judgment for the manufacturer of air conditioning equipment based on the 'sophisticated user' defense. At issue in Johnson was whether the defendant manufacturer of air conditioning equipment had a duty to warn the plaintiff, an air conditioning repairman, about the dangers of brazing refrigerant lines. Brazing, or welding, refrigerant lines can create phosgene gas, the inhalation of which can result in potentially fatal lung disease. Phosgene gas can be detected three ways: 1) through its fresh-cut grass smell; 2) through changes in flame color during brazing; or 3) through physical symptoms like burning eyes and shortness of breath.

The plaintiff in Johnson was an experienced HVAC (heating, ventilation, and air conditioning) technician. Under federal law, HVAC technicians that work on commercial equipment must be certified by the EPA. The plaintiff had this certification, 1 year of study in HVAC systems at ITT Technical Institute, and several years of on-the-job training and experience. The plaintiff claimed that he was injured while brazing refrigerant lines due to exposure to phosgene gas. His lawsuit claimed that the defendant manufacturer failed to provide an adequate warning that brazing refrigerant lines could result in the creation of phosgene gas.

Evidence presented by the defendant manufacturer showed that experienced HVAC technicians know that brazing refrigerant lines can create phosgene gas. Indications that phosgene gas is present ' the fresh-cut grass smell, the green brazing flame, the physical symptoms ' are well known in the industry. A study guide for EPA certification warns of the dangers of brazing refrigerant lines and the creation of phosgene gas. The Material Safety Data Sheet ('MSDS') for the refrigerant used by the plaintiff warned that heating the refrigerant can release toxic gases.

Based on that evidence, the Johnson court found that the defendant manufacturer did not have a duty to warn the plaintiff that brazing refrigerant lines could create phosgene gas and cause injury because the manufacturer could reasonably expect that HVAC technicians would know of the risk. The foundation for this finding is the sophisticated user defense. The sophisticated user defense holds that 'there is ordinarily no duty to give warnings to members of a profession against generally known risks. There need be no warning to one in a particular trade or profession against a danger generally known to that trade or profession.'

Courts that have adopted the sophisticated user defense often cite to the Restatement Second of Torts '388. Under that provision, the suppliers of chattels can be liable to users of those chattels 'if the supplier (a) knows or has reason to know that the chattel is or is likely to be dangerous for the use for which it is supplied, and (b) has no reason to believe that those for whose use the chattel is supplied will realize its dangerous condition.' Comment k to Clause (b) explains: 'One who supplies a chattel to others to use for any purpose is under a duty to exercise reasonable care to inform them of its dangerous character … if, but only if, he has no reason to expect that those for whose use the chattel is supplied will discover its condition and realize the danger involved.' According to the Johnson court, Clause (b) 'has been interpreted to mean that there is no duty to warn if the user knows or should know of the potential danger, especially where the user is a professional who should be aware of the characteristics of the product.'

The Johnson opinion is a good primer on the sophisticated user defense; it provides several string citations that collect a number of cases, both pre and post-Restatement, that have addressed the defense, its origins, and its variations, over the years. Here is a sampling of those cases and their holdings:

  • Littlehale v. E. I. du Pont de Nemours & Co., 268 F. Supp. 971 (S.D.N.Y. 1966) (product at issue ' blasting caps): 'Moreover, there is ordinarily no duty to give warning to members of a profession against generally known risks. 'There need be no warning to one in a particular trade or profession against a danger known to that trade or profession.”
  • Crook v. Kaneb Pipe Line Operating Partnership , 231 F.3d 1098 (8th Cir. 2000) (product at issue ' propane gas): '[T]he decedent, [his coworker and his employer] were experienced professionals in dealing with propane. This rule of the 'sophisticated user' is no more than an expression of common sense as to why a party should not be liable when no warnings or inadequate warnings are given to one who already knows or could reasonably have been expected to know of the dangers of propane.'
  • Parker v. State , 105 N.Y.S.2d 735, 741 (1951) (product at issue ' blood plasma): 'There is a manifest distinction between selling a medical preparation to the public, who may have no knowledge of the dangers attendant upon its use, and making available a preparation to a hospital at its request, whose physicians may be expected to have knowledge of the dangers involved in utilizing the therapeutic preparation ordered by them. Ordinarily, there is no duty to give warning to the members of a profession against generally known risks.'
  • Thibodaux v. McWane Cast Iron Pipe Co ., 381 F.2d 491, 495 (5th Cir. 1967) (product at issue ' cast iron pipe): '[T]he consulting engineers were familiar with or chargeable with the knowledge of the corrosion characteristics of [the manufacturer's] pipe and that such facts were properly within the scope of their own responsibility and expertise. We therefore conclude that [the manufacturer] was under no obligation to inform them of such … '
  • Akin v. Ashland Chemical Co. , 156 F.3d 1030, 1037 (10th Cir. 1998) (product at issue ' chemical solvents): '[T]here is no duty to warn members of a profession against dangers generally known to members of that profession … Because of the wealth of research available, the ability of the Air Force to conduct studies, and its extremely knowledgeable staff, we find that the Air Force easily qualifies as a 'knowledgeable purchaser' that should have known the risks involved with low-level chemical exposure. Employees of the Air Force are also deemed to possess the necessary level of sophistication, so that defendants had no duty to warn the Air Force or its employees of the potential hazards.'
  • Billiar v. Minnesota Mining & Manufacturing Co. , 623 F.2d 240, 243 (2nd Cir. 1980) (product at issue ' electrical resin): 'When the user is fully aware of the nature of the product and its dangers, however, the supplier cannot be held liable for failure to warn them … The rationale behind the 'knowledgeable user' exception is that knowledge of the danger is equivalent to prior notice; no one needs notice of that which he already knows.'
  • Hall v. Ashland Oil Co ., 625 F. Supp. 1515, 1520 (D. Conn. 1986) (product at issue ' benzene): 'In tort law, one with a duty to warn is not liable for failing to warn a party of facts that the party already knew … The theory of this exception is that a failure to warn a party of a danger of which it was independently aware cannot be the proximate cause of injury resulting from that danger, since presumably the party would not have acted differently even if warned.'

As the Johnson opinion and the above summaries highlight, the application of the sophisticated user defense can be broad-ranging, across a number of different products and a number of different professions. So the next time a client calls with a new product liability case, don't forget to check the sophisticated user defense.


Kimberly H. Clancy is an associate at the Los Angeles office of Sidley Austin LLP. She practices in the firm's products liability group.

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