Nail guns: speed before safety.

Since the 1950s, builders have used a variety of powered mechanisms to drive nails and staples. These include simple mechanical springs, explosive-gas-powered guns, compressed-gas-powered guns, rifle-cartridge-powered guns, and air pneumatic guns. With the exception of guns for driving nails into concrete, which still often use firearm cartridges, the most popular method today by far is the air pneumatic gun.

The industry takes pains to avoid having its nail and staple guns referred to as "guns." They are advertised as "nailers," "staplers," "fastener drivers," "fastener tools," or anything else that avoids the association with firearms implied by their common name and invited by their potential dangers.

The injuries resulting from nail gun design flaws are often relatively minor, such as puncture wounds to the feet, hands, legs, and other nonvital body parts. However, at least a few serious injuries or deaths occur each year due to design defects.

These usually happen when workers bump themselves or co-workers with guns while moving about in the workplace, resulting in nails in the heart, head, elbows, and knees. Nails may penetrate the wood and fly through the air to strike a worker in the eye or other body part. And the guns may double-fire (discharge more than one nail in rapid succession when only one is intended), resulting in nails ricocheting through the air and causing injury.

Nail guns have gone through several generations of firing mechanisms, some more hazardous than others. Unfortunately, most manufacturers have opted for speed rather than safety: The safest design has been abandoned by most companies in favor of one that allows nails to be driven more quickly - but also poses more dangers to the user.

Early Designs

In the early development of pneumatic nail guns, they were designed to fire like a pistol: The user would pull the trigger and a nail would fire, whether or not the gun was in place against wood. In later models, the trigger was replaced with a firing mechanism located in the nose of the gun. When this mechanism, called a contact trip, was placed against the wood, the gun would fire. This was known as the bottom-fire design.

Because of the obviously dangerous nature of these designs, they were combined to create a safer nail gun equipped with both a trigger and a contact trip. The gun would then fire only if the contract trip - some makers called it a safety - was depressed first, followed by the trigger. To fire another nail, the trigger had to be released, and the sequence - contact trip first, trigger second - had to be restarted. This became known as the sequential-trigger or restrictive-trigger design, depending on the manufacturer.

This design was common until another change swept the industry during the 1960s and early 1970s, when manufacturers developed what amounted to a semiautomatic-weapon design. The new design allowed the contact trip and the trigger to be depressed in either order. Senco Products, Inc., the largest nail gun maker in the world, calls this the bottom-fire/trigger-fire design because the gun can be shot either by striking the bottom (or nose) against the wood with the trigger pulled or by pulling the trigger after placing the bottom against the wood.(1)

Patent applications filed by Senco in 1966(2) and by Stanley-Bostitch, Inc., in 1972(3) - and perhaps by other makers as well - describe potential hazards of the bottom-fire/trigger-fire firing mechanism. The Senco application stated that the restrictive-trigger design was entirely satisfactory from the safety standpoint, but the new design would allow nails to be fired faster. The same document admitted that safety suffers as nail guns become faster and fire larger nails.

The bottom-fire/trigger-fire design has proved to be dangerously defective in two ways. First, guns equipped with this mechanism are prone to double-fire.

This is because the nail gun tends to recoil after firing the first nail and reset the safety while the gun is still being pushed toward the wood and while the user's finger is still depressing the trigger. The Senco patent application for the bottom-fire/trigger-fire design predicted this problem.

The other drawback of this design is that because the user often carries the gun with a finger on the trigger, any accidental bumping of the gun's nose can cause a nail to fire into the bumped object or person. Senco acknowledged this problem in a 1976 patent application for a device intended to prevent accident "bump-fire" injuries.(4)

The device, which prevented the gun from firing if the trigger was depressed for more than a few seconds, was never put into production. But the patent application acknowledged that the bump-fire potential constitutes a safety hazard. Safety experts have observed that the pistol-grip handle for these guns invites, if not requires, operators - especially those with large hands - to hold the gun with a finger on the trigger.

In 1972, Stanley-Bostitch, Inc. - one of the major manufacturers of nail guns - concluded that safety considerations, and perhaps new standards, would soon require the industry to equip nail guns with the restrictive-trigger mechanism. Perhaps Bostitch recognized that this was the only way to avoid the substantial risk of injury inherent in the semiautomatic design. For that model year, Bostitch changed the firing mechanism on its main product lines of nail guns from the bottom-fire/trigger-fire design to the restrictive-trigger design.

Naturally, some customers balked at this because they were used to the speed of the faster but much more dangerous bottom-fire/trigger-fire models. In 1973, Bostitch began retrofitting the new guns with the faster mechanism. Bostitch and the other manufacturers now point to this attempt to sell safer guns over 20 years ago as proof that customers will not stand still for the safer design.

More broadly, the standard arsenal of defenses includes the notion that these products are intended for industrial use and need to be dangerous to meet the demands of U.S. industry. Defendants sometimes argue that our nation's place in world industrial competition is in jeopardy if manufacturers are required to sell safer nail guns.

Safety Standards 

Beginning in the late 1970s, several European countries, New Zealand, and Australia adopted standards requiring nail guns that fire nails greater than a minimal length to be equipped with restrictive triggers. U.S. government agencies, on the other hand, have not yet addressed safety concerns related to nail guns. A Consumer Product Safety Commission inquiry into nail gun safety during the Reagan years ended when the industry convinced the agency that nail guns are a commercial product with consumer sales not constituting a significant part of the market.

Outside the government, the products are regulated in the United States under the American National Standards Institute (ANSI) voluntary standards adoption process which for nail guns is controlled by the International Staple and Nail Tool Association (ISANTA), an industry group. The standards that have been promulgated by this method are only as strong as ISANTA allows them to be. Thus, the only standards adopted are those the industry already meets, and these will never modify industry practices.

No serious consideration seems to have been given to any requirement for safer triggering mechanisms. This is so even though a standard would relieve each manufacturer of the fear that if it were to change to the safer design it would lose competitive advantage among customers concerned about the speed of nailing operations.

Although the lack of U.S. standards is disturbing, the existence of foreign standards provides attorneys with the opportunity to develop evidence that the manufacturers have had notice of nail gun safety issues for some time. However, the future of foreign regulation of these products is in doubt.

As part of the standardization of laws under the jurisdiction of the Committee for European Normalization, a standards-making process is ongoing. Senco and probably other U.S. and foreign manufacturers are actively involved in efforts to persuade the European regulatory agency to eliminate mandatory restrictive-trigger standards, rather than make the standard a uniform requirement for the European Economic Community. Because the countries, standards differ substantially and because the manufacturers seem committed to destroying the beneficial safety standards, it would not be surprising if the desire for uniformity outweighs the interests of safety and a meaningless standard results.

Case Strategies

The following litigation strategies will help attorneys representing injured victims build strong cases against nail gun manufacturers.

Examine product documentation. It has been more than 20 years since the trend away from the relatively safe restrictive-trigger nail guns toward the remarkably dangerous bottom-fire/trigger-fire guns began. Since then, the industry has known that the faster design would cause guns to double-fire and to fire unintentionally when they are bumped into objects or people.

Despite the industry's decision to accept those risks on behalf of nail gun users, manufacturers made no effort during those 20-plus years to advise buyers, users, or regulators of the dangers inherent in the bottom-fire/trigger-fire guns. Generally, they have not even disclosed that the safer design exists.

Senco, for example, has published owner's manuals, labels, and other documentation for years that mention the restrictive-trigger device only in a passing reference to its usefulness for accurate nail placement. These materials never hint that the restrictive-trigger model also has major safety advantages over the standard model.

Bostitch has published in its owner's manuals a list of "positive safety advantages" of its restrictive-trigger model compared to its bottom-fire/trigger-fire design (which it calls the contact-trip design). But, as evidence in litigation has disclosed, this was more lip service than a real effort to promote safety. Because the advantages are disclosed in the owner's manual, users learn of them only after they have purchased a nail gun - usually one with the more dangerous design. If Bostitch had intended an effective warning, it would have conveyed the information before the purchase occurred so the buyer could exercise a real choice.

To demonstrate the manufacturers' knowledge of safety hazards and their failure to inform users about them, counsel should thoroughly explore the history of restrictive- and nonrestrictive-trigger devices for the model and brand of gun involved in the case. Counsel should try to obtain all patents sought or received for these devices or licensed from other patent holders.

Through discovery or other means, the attorney should gather copies of all manuals, brochures, or other publications for the subject model and year, as well as for all available predecessor and successor models and years. Comparing the defense claims to the language used in the publications to describe the triggering choices may show some glaring discrepancies.

For example, Senco claims it has offered its restrictive-trigger models for users who want a safer but slower gun. Yet, the only mention of this alternative in the company's publications says that it is "useful when precise fastener placement is required." Counsel may get the impression that the safer restrictive-trigger models are part of the product line (if they are at all) only to provide a defense that says customers choose not to buy and use the safer type.

Investiqate testing efforts. Responsible manufacturers who learn that their products can be made safer at least perform engineering tests and market surveys to discover the potential for injury from the less safe design. However, Senco has apparently never tested to discover, quantity, or qualify the double-fire potential of any of its products.

Responsible tool manufacturers who believe that the building industry needs a fast but unsafe product at least ought to test safer alternative designs to learn whether they can satisfy customers' needs. However, in a case I handled recently, Senco acknowledged that it had not analyzed whether the industry would accept the safer but slower design during the 24 years before my client was serously injured by a bottom-fire/trigger-fire nail gun.(5)

Nail guns available today are capable of firing as many as nine nails over three inches long in a second. Manufacturers maintain that this speed is required by the customers they serve. Yet in the case mentioned above, Senco conducted no testing of the need for this speed until three years after the model that injured my client was placed on the market in 1989. When testing was done, it showed that the guns could easily be modified to fire not more than seven nails per second, with substantial improvement in safety and no meaningful loss in product utility. The absence of this kind of inquiry during the 20 years before the injury helped prove the company's disregard for safety.

Defendants insist they should not be required to produce discovery of testing or design and development efforts for products other than the model involved in the injury. The truth is that the firing mechanisms for most brands and models have not changed materially since the first bottom fire/trigger-fire mechanisms were developed 20 or more years ago. Therefore, the history of every product equipped with that mechanism during that time is essential to the plaintiff's proof of the negative: that the manufacturer did not perform reasonable testing, failure analyses, or follow-up studies.

Without broad discovery, the company may claim that it relied on the testing of a predecessor product rather than test the present product separately. Also counsel is likely to miss important admissions about conclusions the company may have made years ago confirming the unsafe nature of the design.

Share information. Anecdotal evidence strongly suggests that nail gun manufacturers have subordinated their competitive urges to their common interest in avoiding liability. It is not coincidental that ISANTA takes a position against any modification of voluntary standards that might require its members to produce safer products. Employees of one manufacturer have even testified for another company in the defense of the safety of the competitor's practices and products.

As always, plaintiffs, lawyers should share as much information as possible and resist protective orders to overcome this united defense front. They also must continue efforts to obtain ISANTA documents and testimony of its representatives from legislative and regulatory hearings and litigation.

Safer Alternatives

An injured worker's case against a nail gun manufacturer can be made stronger by showing that safer design alternatives existed but the defendant ignored them. Several safer nail gun designs are available. The most obvious alternative is the restrictive-trigger mechanism.

Another alternative is simply to reduce the firing speed of the semiautomatic nail gun and to place limitations on its intended use. Experts have testified that a possible solution to the double-firing problem is to make clear (for example, with a simple large-letter label on the gun) that the bottom-fire/trigger-fire guns should not be used for single firing. (This is also called place firing, which refers to when the gun is pushed against the wood first, before the trigger is pulled, to put one nail accurately in place.) This solution would prevent most ricochet accidents and the loss of control from excessive recoil after a second nail hits the first nail.

Of course, labels do not prevent consumers from using a tool inapproptiately. But they can give users a chance to modify their behavior for their own safety-a chance currently being denied them.

Another modification that can reduce the double-fire risk is to lighten the spring tension on the contact trip on the nose of the gun. Ironically, this runs counter to the ANSI standard, which requires the contact trip to support at least the full weight of the loaded gun.(6) The effect of less spring tension would be to reduce the amount of forward pressure against the wood necessary to make the gun fire. This would improve the chance that the gun would recoil clear of the wood, so that the nose spring would not reset and refire the gun.

Another way to protect against double-fire injuries would be to provide a switch on the gun that would allow the user to choose which firing mode to employ. The technology to do this has been used in military rifles, such as the M-14 and the M-16, since the Korean War. Patent searches will turn up electronic control devices designed in the 1980s for nail guns. These devices can switch the gun's firing mechanism from restrictive trigger to bottom fire/trigger fire or vice versa.

Workers using nail guns equipped with this type of switch would have the option of using the gun in a safe but slightly slower mode or the faster but more dangerous mode. They could be made aware of the safety benefits of the restrictive-trigger mode for single-firing applications.

Nothing short of eliminating the bottom-fire/trigger-fire mechanism will prevent the bump-fire hazard. But the manufacturers maintain that this would remove the rapid nailing capability of these products. Framing contractors agree. They do indeed make quick work of nailing flooring, sheathing, decking, wallboards, and other materials that do not require much concern for precise nail or staple placement.

However, modifications are technically feasible to greatly decrease the bump-fire hazard. One is to provide a protective cage or shield around the contact trip so that it will not fire nails from the gun unless it is bumped from a direct frontal angle.

Another is to equip the gun with a timing device like the one patented by Senco in 1976. This device would prevent the gun from firing within a few seconds after the trigger is pulled. Senco claims this design was never produced because of its low reliability against failure, but the company admits it was never tested for reliability.

The nail gun industry has succeeded in avoiding liability so long and so well that manufacturers have not seen a reason to put meaningful resources into research and development of safer nail guns. More successful litigation against manufacturers is probably going to be the key to turning this problem around.

Notes (1) Senco developed its products in this sequence. However, the opinion of the Eighth Circuit in Drabik v. Stanley-Bostitch, Inc., 997 F.2d 496, 500-01 (8th Cir. 1993), indicates that Bostitch had the bottom-fire/trigger-fire design first, then developed the restrictive-trigger mechanism as a safety, change in the early 1970s. See U.S. Patent No. 3,784,077 (May 5, 1972). (2) U.S. Patent No. 3,278,106 (Oct. 11, 1966). (3) U.S. Patent No. 3,784,077 (May 5, 1972). (4) U.S. Patent No. 3,964,659 (June 22, 1976). (5) Lakin v. Senco Prods., Inc., No. 9211-07901 (Or., Multnomah County Cir. Ct. Feb. 4, 1994). (6) See ANSI/SANTA standard SNT-101-1983, 4.3.2.