Southland Mower Company v. Consumer Product Safety Commission, John O. Hayward v. Consumer Product Safety Commission

Approximately 77,000 people are injured each year in the United States by contacting the blades of walk-behind power mowers. 1 Of these injuries, an estimated 9,900 involve the amputation of at least one finger or toe, 11,400 involve fractures, 2,400 involve avulsions (the tearing of flesh or a body part), 2,300 involve contusions, and 51,400 involve lacerations. The annual economic cost inflicted by the 77,000 yearly blade-contact injuries has been estimated to be about $253 million. This figure does not include monetary compensation for pain and suffering or for the lost use of amputated fingers and toes. 2

To reduce these blade-contact injuries, the Consumer Product Safety Commission (“CPSC” or “the Commission”) promulgated 3 a Safety Standard for Walk-Behind *503 Power Lawn Mowers, 16 C.F.R. Part 1205 (1979), 44 Fed. Reg. 9990-10031 (Feb. 15, 1979), pursuant to section 7 of the Consumer Product Safety Act (“CPSA” or “the Act”), 15 U.S.C. § 2056 (1976). 4 In the present case we consider petitions by the Outdoor Power Equipment Institute (“OPEI”), manufacturers of power lawn mowers, 5 and an interested consumer to review 6 the Safety Standard for Walk-Behind Power Lawn Mowers.

The standard consists of three principal provisions: a requirement that rotary walk-behind power mowers pass a foot-probe test, 16 C.F.R. § 1205.4, 44 Fed. Reg. 10025-26, a requirement that rotary machines have a blade-control system that will stop the mower blade within three seconds after the operator’s hands leave their normal operating position, 16 C.F.R. § 1205.5(a), 44 Fed. Reg. 10029, and a requirement, applicable to both rotary and reel-type mowers, that the product have a label of specified design to warn of the danger of blade contact, 16 C.F.R. § 1205.6, 44 Fed. Reg. 10029-30. The standards also contain additional directives that are intended to increase the effectiveness of the primary regulations. Thus, because the foot-probe provision can be satisfied by shielding the blade area, the standard mandates tests to assure that shields have a certain minimum strength, 16 C.F.R. § 1205.4(a)(2), 44 Fed. Reg. 10026-28, and that a shielded mower can traverse obstructions. 16 C.F.R. § 1205.4(a)(3), 44 Fed. Reg. 10028-29. The standard also stipulates that shields that move to permit attachment of auxiliary equipment must either automatically return to their normal position when the supplemental equipment is not attached or prevent blade operation unless the shield is manually returned to its normal position when the added equipment is not used. 16 C.F.R. § 1205.4(c). Similarly, the three-second blade-stop requirement is supported by ancillary instructions that mowers employing engine cutoff to halt the blade have power restart mechanisms, 16 C.F.R. § 1205.5(a)(iv), and that all mowers have a control that must be activated before the blade can resume operation in order to prevent the blade from accidentally restarting. 16 C.F.R. § 1205.5(a)(2).

OPEI challenges the legality of the standard by contending that it includes *504 nonconsumer products within its scope of regulation, as well as unique consumer products not proven to present the same hazards as typical consumer lawn mowers. OPEI also argues that substantial evidence on the record as a whole 7 does not support the Commission’s determination that the foot-probe and shielding requirements “are reasonably necessary to reduce or eliminate an unreasonable risk of injury” 8 associated with walk-behind power lawn mowers. In addition, OPEI attacks the blade-stop requirement on the grounds that it is a design restriction rather than a performance requirement, imposes criteria that can only be satisfied by technology that is currently unsafe and unreliable, and mandates a three-second blade-stopping time that is not justified by substantial record evidence. OPEI further asserts that the labeling requirement is invalid because its issuance is not authorized by section 27(e) of the Act, 15 U.S.C. § 2076(e), and it lacks the substantial evidentiary support necessary for it to be promulgated under section 7(a)(2) of the Act, 15 U.S.C. § 2056(a)(2). Finally, OPEI urges that the standard’s effective date is unfeasibly early and that, in any event, substantial record evidence fails to establish that the benefits of the standard bear a reasonable relationship to its costs and demonstrate that the rule is reasonably necessary and in the public interest. Consumer advocate Hayward, on the other hand, claims that the blade-stopping time chosen by the Commission is too slow and that the effective date imposes unnecessary delay. We shall examine each of these objections to the standard in the following discussion.

Scope of the Standard

The CPSC may regulate only “consumer products.” 15 U.S.C. §§ 2052(a)(1), 2058(a)(1). 9 See ASG Industries, Inc. v. Consumer Product Safety Commission, 593 F.2d 1323, 1327 (D.C.Cir.1979); Consumer Product Safety Commission v. Anaconda Co., 593 F.2d 1314, 1317 (D.C.Cir.1979); Kaiser Aluminum & Chemical Corp. v. Consumer Product Safety Commission, 574 F.2d 178, 179-81 (3d Cir.), cert. denied, 439 U.S. 881, 99 S.Ct. 218, 58 L.Ed.2d 193 (1978). As *505 defined by the Act, a consumer product is an article, or component thereof,

produced or distributed (i) for sale to a consumer for use in or around a permanent or temporary household or residence, a school, in recreation, or otherwise, or (ii) for the personal use, consumption or enjoyment of a consumer in or around a permanent or temporary household or residence, a school, in recreation, or otherwise, but . . . not . . . (A) any article which is not customarily produced or distributed for sale to, for use or consumption by, or enjoyment of, a consumer .

15 U.S.C. § 2052(a)(1).

OPEI asserts that the Commission exceeded its statutory authority by attempting to regulate lawn mowers that are not consumer products and by failing to exclude “unique” products, such as high-wheel and three- or five-wheel mowers, that differ significantly from the typical mower used by consumers and that allegedly were not shown by substantial evidence to need regulation in order to eliminate or reduce an unreasonable risk of harm. We find, however, that the safety regulation’s coverage is not impermissibly broad. The standard expressly states that: “Except as provided in paragraph (c) of this section, all walk-behind rotary and reel-type power lawn mowers manufactured or imported on or after the effective date of the standard are subject to the requirements of this standard if they are ‘consumer products’ . . . [as defined in section 3(a)(1) of the CPSA, 15 U.S.C. § 2052(a)(1)].” 16 C.F.R. § 1205.-1(b)(1) (emphasis added). Thus, if a lawn mower is not customarily produced or distributed for sale to, or use or consumption by, or enjoyment of, a consumer, it is ab initio not covered by the standard.

In addition, the standard excludes 10 from regulation mowers that are 30 or more inches wide, weigh 200 or more pounds, and, if engine powered rather than electric, have an engine with eight or more horsepower. 16 C.F.R. § 1205.1(c)(1). Even if the marketing and usage patterns of these larger machines do not automatically place them outside the standard’s coverage of consumer products, they are nevertheless excused from its requirements in recognition of the greater burden that compliance would impose on manufacturers of these units and of their less frequent use by consumers. 11 The

*506 standard’s statement of scope establishes that, in prescribing lawn mower safety measures, the CPSC acted within its authority and sought to regulate only consumer products.

OPEI’s claim that substantial record evidence does not justify application of the standard to “uniquely” designed consumer lawn mowers, 12 such as high-wheel, three-wheel and five-wheel mowers, mowers with nonmetal blades, and air-supported mowers, is also without merit. Sufficient evidence clearly establishes that, as a general category of consumer products, walk-behind power mowers are sufficiently hazardous to justify their regulation by a consumer product safety standard. The Commission ruled that three-wheel, five-wheel, high-wheel, and air-supported rotary mowers were included in the standard because: “The number of wheels or the use of an air cushion instead of wheels would appear to have little relevance to the likelihood of contact with the rotating lawn mower blade. These mowers could present the same risks of blade contact as the common four-wheel rotary mower.” 44 Fed. Reg. 9990, 9997-98 (Feb. 15, 1979). It further decided that mowers with semi-rigid or rigid blades made of nonmetal material, such as plastic or rubber, fell within the standard’s coverage. The Commission reasoned that

[N]o convincing evidence has been presented ... to show that these blades present a different risk of injury than metal blades. If these blades are rigid or semi-rigid, they appear to present an unreasonable risk of amputation, laceration, fracture, or avulsion in the same manner as metal blades. Blades typically rotate at a top speed of approximately 200 mph and a hand or foot struck by a semi-rigid or rigid blade made of material other than metal, that also cuts grass, can be expected to cause the same types of injuries as a metal blade.

Id. at 9998.

The Commission may treat “a range of similar products as a single product class” if they “exhibit . . . sufficient similarity of functional and risk characteristics.” ASG Industries, Inc. v. Consumer Product Safety Commission, 593 F.2d 1323, 1330 (D.C.Cir.1979), cert. denied, 444 U.S. 864, 100 S.Ct. 133, 62 L.Ed.2d 87 (1979) (emphasis added). The task of evaluating function and risk factors to determine product classification for purposes of inclusion within a safety standard “is committed primarily to the judgment of the Commission.” Id. See 15 U.S.C. § 2058(c)(1). 13 However, the Commission does have “a responsibility to justify application of the standard to a product or product use that, according to the facts elicited in the course of rulemaking, exhibits significantly dissimilar functional or risk characteristics when compared with the other products covered by the standard.” ASG Industries, Inc. v. Consumer Product Safety Commission, 593 F.2d at 1330. 14 In the face of apparent *507 functional or risk characteristics that distinguish one group of products from another, justification for general regulation may be provided by a reasoned decision either "(1) that the product presents no significantly dissimilar functional or risk characteristics pertinent to the objectives of the standard; or (2) that despite significant differences, application of the standard to the product remains ‘reasonably necessary to prevent or reduce an unreasonable risk of injury associated with such product . . . ” Id. (emphasis added).

In the present case no evidence was introduced to show that the so-called “unique design” or “specialty” mowers were significantly dissimilar in function or risk characteristics from the typical walk-behind power lawn mower studied by the Commission. As the Commission determined, these mowers have rotating, hardcutting blades that produce the hazards addressed by the safety standard. Thus, the unique design machines are part of the general product category of walk-behind power lawn mowers, and in the absence of any evidence pointing to features differentiating their risk or function characteristics for purposes of protecting consumers from blade-contact injuries, the Commission properly included them in the standard. See Bunny Bear, Inc. v. Peterson, 473 F.2d 1002, 1007 (1st Cir. 1973). 15

*508 Foot-Probe and Shielding Requirements

The standard mandates that walk-behind power rotary mowers pass a foot-probe test designed to assure that the machine guards the operator’s feet against injuries caused by contact with the moving blade. The test requires that a probe simulating a human foot be inserted along the rear 120 degrees of the mower and at the discharge chute without coming into contact with the blade when inserted. 16 C.F.R. § 1205.4, 44 Fed. Reg. 10025-26. See also Fed. Reg. 10001-10002. Mowers meet the foot-probe test by having shields that prevent the probe from entering the blade’s path. 16 C.F.R. § 1205(aXl), 44 Fed. Reg. 10025.

OPEI does not deny that a foot-probe test for the rear area of the mower is reasonably necessary to reduce injuries. 16 Rather, it asserts that application of the test to the discharge chute is not supported by substantial record evidence. It alleges that the injury data does not show that foot injuries occur at that location and that it would be theoretically impossible for an operator to suffer a foot injury at the discharge chute while holding the “deadman’s” blade-control 17 switch on the mower handle. 18

The Act requires that safety standards be supported by “substantial evidence on the record as a whole.” 15 U.S.C. § 2060(c). 19 The foot-probe provision can be sustained only if the record contains “ ‘such relevant evidence as a reasonable mind might accept as adequate to support a conclusion’ ” that an unreasonable risk of foot injury exists from blade-contact at the discharge chute, that the foot-probe test will ameliorate it, and that the benefits of this proposed reform make it reasonable in light of the burdens it imposes on product manufacturers and consumers. Aqua Slide ‘N’ Dive v. Consumer Product Safety Commission, 569 F.2d 831, 838-40 (5th Cir. 1978) [hereinafter cited as Aqua Slide] (quoting Consolidated Edison Co. v. NLRB, 305 U.S. 197, 229, 59 S.Ct. 206, 216, 83 L.Ed. 126 (1938)).

The determination of whether an unreasonable risk of discharge-chute injury exists involves “a balancing test like that familiar in tort law: The regulation may issue if the severity of the injury that may result from the product, factored by the *509 likelihood of the injury, offsets the harm the regulation imposes upon manufacturers • and consumers.” Aqua Slide, 569 F.2d at 839 (quoting Forester v. Consumer Product Safety Commission, 559 F.2d 774, 789 (D.C. Cir. 1977) (defining “unreasonable risk” in case brought under the Federal Hazardous Substances Act, 15 U.S.C. §§ 1261-74 (1976), and referring to “similar language” and legislative history of CPSA for support)). 20 See H.R.Rep.No.1153, 92d Cong., 2d Sess. 33 (1972); 21 Note, The Consumer Product Safety Commission: In Search of a Regulatory Pattern, 12 Colum.J.L. & Soc. Prob. 393, 401-12 (1976); Note, The Consumer Product Safety Act: Risk Classification & Products Liability, 8 Ind.L.Rev. 846, 849-52 (1975) (citing cases and materials discussing meaning of “unreasonable risk”). Thus, under the unreasonable risk balancing test, even a very remote possibility that a product would inflict an extremely severe injury could pose an “unreasonable risk of injury” if the proposed safety standard promised to reduce the risk effectively without unduly increasing the product’s price or decreasing its availability or usefulness. Aqua Slide, 569 F.2d at 839-40. 22 Conversely, if the potential injury is less severe, its occurrence must be proven more likely in order to render the risk unreasonable and the safety standard warranted.

In the present case, the discharge-chute probe is intended to reduce the risk of such injuries as amputation of toes, fractures of bones in the feet or toes, avulsions, deep lacerations, and contusions. While the seriousness of these injuries cannot be gainsaid, it does not rise to the level of gravity that would render almost any risk, however remote, unreasonable if the risk could be reduced effectively by the proposed regulation. 23 Substantial evidence that such injury is significantly likely to occur is therefore necessary to sustain this portion of the lawn mower safety standard.

Our examination of the record has failed to reveal substantial evidence that injury at the discharge chute was sufficiently probable that it made the risk addressed by the foot probe of this area unreasonable. In a study of 36 blade-contact foot injuries conducted for the CPSC by the National Electronic Injury Surveillance *510 System (NEISS), 24 one injury occurred when the operator inserted his foot into the blade path at the discharge chute while holding the mower handle. This injury represented almost three percent of the blade-contact foot injuries in the sample. However, the study did not involve a random sample, and it is not possible to extrapolate the percentage of total blade-contact injuries represented by discharge-chute incidents involving the operator’s feet from the limited information furnished in the record. In any event, trustworthy statistical inferences cannot be drawn from a single incident of discharge-chute injury. Without reliable evidence of the likely number of injuries that would be addressed by application of the foot-probe test to the discharge chute, we are unable to agree that this provision is reasonably necessary to reduce or prevent an unreasonable risk of injury. See D. D. Bean & Sons Co. v. Consumer Product Safety Commission, 574 F.2d 643, 650-51 (1st Cir. 1978) (hereinafter D. D. Bean) (holding that absence of relevant injury data associated with particular hazards renders requirements of safety standard addressed to them invalid and observing that “a single injury ... is not substantial evidence of an ‘unreasonable risk of injury.’ ”). It must be remembered that “[t]he statutory term ‘unreasonable risk’ presupposes that a real, and not a speculative, risk be found to exist and that the Commission bear the burden of demonstrating the existence of such a risk before proceeding to regulate.” Id. at 651.

Our conclusion that substantial evidence fails to justify this provision is not altered by the fact that the industry’s voluntary standard, ANSI B71.1-1972 § 1968, and ANSI 71.1b-1977 § 11.8, requires probing of the discharge chute. See 44 Fed. Reg. at 10003. A private industry safety standard cannot, by itself, provide sufficient support for a Commission regulation. “ ‘While such private standards may tend to show the reasonableness of similar Commission standards, they do not prove the need for such provisions.’ ” Aqua Slide, 569 F.2d at 844 (quoting Forester v. Consumer Product Safety Commission, 559 F.2d at 793 (emphasis in original)). We therefore vacate that part of the standard requiring the discharge-chute area of power lawn mowers to pass a foot-probe test.

OPEI also attacks certain aspects of the shielding requirements that supplement the foot-probe test as devoid of substantial evi-dentiary support. The standard directs that shielding must pass a shield-strength test in order to assure that shields maintain their structural integrity and remain attached under conditions of use and provide the intended protection. 16 C.F.R. § 1205.-4(a)(2). 25 Similarly, the standard requires that shielded mowers undergo an obstruction test, 16 C.F.R. § 1205.4(b)(2), which simulates surface irregularities that the mower may encounter in normal use. 26 The *511 test is designed to ascertain that the shielding will not interfere with mower performance by catching on obstructions and stopping the mower. It is also intended to prevent the shields themselves from contributing to lawn mower hazards, either by lifting the mower excessively when it meets an obstruction and thus exposing the blade or by suddenly halting the mower and causing it to lift and/or the operator to stumble on it.

The Commission estimates that the foot-probe/shielding requirements, including the supporting strength and obstruction tests, will reduce blade-contact foot injuries by 13,000 incidents each year. It did not apportion this injury reduction among the respective foot-probe shielding requirements on the ground that this was impossible because they are interrelated. The Commission estimates that the shield provisions will cost about $4 per mower, primarily for redesigning shields. Little expense is believed to result from the shield-strength test, since it is similar to a requirement in the existing voluntary industry standard, ASNI B71.1 — 1972 §§ 11.5, 11.15; ANSI B71.1b-1977, §§ 11.5, 13.2.1, which receives almost universal compliance. 27

OPEI readily admits that shielding is necessary to protect operators against blade-contact foot injuries at the rear of the mower. It contends, however, that the shield-strength test is invalid because few injuries have been shown to be caused by inadequately strong shields. OPEI also argues that the possibility that users might

remove the protective shielding if it interfered with mower utility by catching on surface irregularities cannot justify the obstruction test and asserts that the test has not been proven necessary to guard against injuries cause by the mower’s sudden stopping when it catches on obstacles.

We find that OPEI’s approach to the shield-strength test is misconceived. It is true that were this requirement viewed in isolation as intended to address a risk of injury from mower shields falling off or cracking and exposing the operator’s foot to the blade, independent of the standard’s requirement that mowers be equipped with foot-probe shields, the record would not contain sufficient evidence that such injuries are so numerous that they support the regulation. 28 But the shield-strength test is mandated as an ancillary feature of the foot-probe and shielding requirements that in turn are concededly necessary to reduce an unreasonable risk of operator blade-contact foot injuries. The shield-strength provision is not to be understood as a discrete measure addressing a distinct type of operator foot injury but as part of the Commission’s effort to make the shielding remedy itself effective and safe. Since an unreasonable risk .of operator foot injury from blade contact has been established, the shields are reasonably necessary to prevent access to the blade, and the “curative effect” of the shield-strength requirement in preventing blade exposure from inadequate shielding is “patent,” we “do not think that *512 the Commission had to cite empirical data in support of its finding that the particular [shield strength] requirement [was] likely to reduce the risk of injury.” D. D. Bean, 574 F.2d at 649. 29

Our opinion in Aqua Slide, 569 F.2d at 842, lends support to the determination that the shield-strength test can- be justified as logically related to the necessary shielding remedy and as providing a clearly effective remedy for a patent risk of injury from broken shields without a separate “body count” of incidents involving structurally unsound shields. In Aqua Slide we observed that the Commission’s burden to produce empirical evidence showing that a proposed warning sign was a reasonably necessary means of reducing an unreasonable risk “may be especially light” when the warning signs were aimed at first-time adult' and teenage users, making it logically more likely that the signs would be heeded and thus effective in reducing injuries. See also id. at 845 (Wisdom, J., concurring: “ ‘untested theory’ that some people will react and be affected by warning signs . needs little, if any, empirical support to meet the substantial evidence standard. . . . ” when “the message is [included] [for] . . first-time adult and teenage [testers]”).

Moreover, the shield-strength test is a particularly appropriate exercise of Commission authority to implement remedies for unreasonable risks because the hazards that will accompany structurally unsound shielding will not become widely manifest until shielding is generally required for consumer power lawn mowers by the standard. When part of a standard is directed at making sure that required safety measures provide their intended level of protection, and it is clear that if they do not “ ‘it seems conceptually clear that an injury will occur, it is primitive to wait until a number of people have lost their lives, or *513 sacrificed their limbs before we attempt to prevent those accidents.’ . . . [N]o precise statistical showing is required.” Forester v. Consumer Product Safety Commission, 559 F.2d 774, 789 (D.C.Cir.1977) (quoting 1969 Senate Report to the Federal Hazardous Substances Act, S.Rep.No.71,237, 71st Cong., 1st Sess. 2-3 (1969)). We therefore uphold the shield-strength test provision of the standard.

For similar reasons we reject OPEI’s challenge to the obstruction test requirement and find that it is reasonably necessary to guard against intentional consumer defeat of the shielding safety device and to prevent shielding from interfering with mower utility. Although OPEI does not dispute the likelihood that consumers will remove shields if they interfere with mower performance 30 or contest the feasibility of the obstruction test, it does contend that the possibility that consumers may remove protective shielding if it hampers mower utility by catching on surface obstructions does not present the kind of unreasonable risk of injury that the Commission has authority to regulate. In essence, OPEI argues that the risk of injury from consumer defeat of safety shielding is not “unreasonable” because . consumers would have chosen to incur the risk, and their judgment must be respected.

However, Congress intended for injuries resulting from foreseeable misuse of a product to be counted in assessing risk. Aqua Slide, 569 F.2d at 841. See S.Rep.No.92-749, 92d Cong., 2d Sess. 14, 92 Cong.Rec. 36198 (1972) (remarks of Sen. Moss) (risk of injury “associated with” consumer products, 15 U.S.C. § 2052(a)(3), to be regulated by CPSC includes risks of injury resulting from “exposure to or reasonably foreseeable misuse of a consumer product”); Kimber, Federal Consumer Product Safety Act § 94 at 109 (1975). Cf. Pacific Legal Foundation v. Department of Transportation, 593 F.2d 1338, 1345 (D.C.Cir.1979) (Secretary of Transportation required to consider probable public reaction to passive automobile restraints, including possibility of attempts to deactivate them, in promulgating safety standard under National Traffic & Motor Vehicle Safety Act of 1966, 15 U.S.C. §§ 1381 et seq. (1976)). This principle, and not the tort liability concept of “assumption of risk,” governs the Commission’s authority to treat consumers’ foreseeable action of removing safety shields as creating an unreasonable risk of injury and to issue rules addressing that danger. See United States v. General Motors Corp., 518 F.2d 420, 434-35 (D.C.Cir.1975) (“[determinations of fault or liability relevant to the award of damages . . . are not controlling on the interpretation of the” meaning of product “defect” in prophylactic defect notification legislation of National Traffic & Motor Vehicle Act of 1966). Of course, a fully informed choice on the part of consumers to employ a dangerous product may provide information that is relevant to the Commission’s assessment of the reasonableness of a risk of injury. For example, consumers’ decisions to use sharp knives may pose a reasonable risk of injury because duller knives, while safe, would be useless for cutting purposes, and the Commission could reasonably find that consumers have accurate information of the severity and likelihood of injury posed by sharp knives. See Aqua Slide, 569 F.2d at 839; S.Rep.No.92-749, supra at 6-7. In the present case, however, there is no evidence that consumers accurately appreciate the nature of the risk of blade-contact injuries and that their presumed willingness to defeat protective measures is reasonable.

The record contains substantial evidence, in the form of comment letters from both consumers and consulting engineers, that shields on some mowers interfered *514 with the machine’s mobility and consequently were removed by their owners, thus eliminating any safety benefits they were intended to provide. Since a risk of blade-contact injury is clearly created by removing the protective shields and the risk can be effectively reduced by eliminating the annoyance imposed by shields that interfere with mower movement, it was proper for the standard to include an obstruction test to reduce the risk of this foreseeable misuse of lawn mowers.

The obstruction test is valid also as a measure designed to assure that shielding is feasible as a method of reducing the risk, see Aqua Slide, 569 F.2d at 839; Forester v. Consumer Product Safety Commission, 559 F.2d at 789 n.21, and does not inordinately interfere with mower utility. In promulgating a safety standard, the Commission must consider the “probable effect of such rule upon the utility ... of such products . . .” 15 U.S.C. § 2058(c)(1)(C) (emphasis added). See Aqua Slide, 569 F.2d at 839; H.R.Rep.No.1153, 92d Cong., 2d Sess. 33 (1972). In order to fulfill its statutory responsibility to determine that the requirements of a safety standard will not unreasonably reduce product usefulness, the Commission must have authority to establish performance criteria for its chosen remedies. Therefore, the obstruction test, as a component- of the foot-probe/shielding requirements, is reasonably necessary to ensure that mowers satisfy the standard in ways that do not decrease the product’s utility. Accordingly, we uphold the obstruction-test provision.

Blade-Control System

The second key element of the standard requires a blade-control system that (1) will prevent the blade from rotating unless the operator activates a control, (2) allows the blade to be driven only if the operator remains in continuous contact with the “deadman’s” control, and (3) causes the blade to stop moving within three seconds after the deadman’s control is released. 16 C.F.R. § 1205.5. In addition, the standard directs that engine-powered mowers with only manual starting controls must have a blade-control system that stops the blade without turning off the engine. This requirement is intended to reduce the temptation for consumers to disable the blade-control mechanism in order to avoid the inconvenience of having to restart the engine manually each time the deadman’s switch is released. Also, all walk-behind rotary power mowers must have a separate restart mechanism as well as an initial ignition device in order to prevent inadvertent starting of the blade by accidental activation of the primary ignition control. The controls must be located in an “operator control zone” at the rear of the mower so that during normal use, including starting efforts, the operator generally will be behind the mower handle. Id.

The blade-control system is intended to protect the operator against blade-contact injuries to both hands and feet by stopping the blade before the operator can contact it after he or she leaves the normal operating position and thus releases the deadman’s control. 31 The Commission estimates that the blade-control provisions will eliminate approximately 46,500 operator blade-contact injuries a year. This figure represents approximately 60 percent of all blade-contact injuries and nearly 80 percent of all injuries claimed to be reduced by the standard. As OPEI acknowledges, the blade-contact requirements thus are the “centerpiece” of the Commission’s strategy for reducing blade-control injuries.

Perhaps as befits its importance in the regulatory scheme promulgated by the Commission, the blade-control system is vigorously attacked by both OPEI and consumer proponents of stricter safety requirements. OPEI asserts that the blade-control *515 system provision is expressed as a design requirement, rather than as a performance requirement, in violation of the Act. It argues that a number of alternative requirements are available that are less design restrictive and more performance oriented than the blade-stop criterion and that the Commission therefore erred in adopting the blade-stop approach. OPEI further contends that the standard is unreasonable because it requires the use of mechanisms that allegedly are not safe or reliable. And, OPEI claims, the three-second stopping time is unreasonably short. In contrast, consumer advocate John 0. Hayward maintains that the three-second blade-stopping time is too lax and that substantial evidence demonstrates that only a two-second or shorter blade-stopping time is justified.

The CPSA directs that a safety standard’s provisions “shall, whenever feasible, be expressed in terms of performance requirements.” 15 U.S.C. § 2056(a). The statutory preference 32 for performance requirements is rooted in the belief that this mode of regulation stimulates product innovation, promotes the search for cost-effective means of compliance, and fosters competition by offering consumers a range of choices in the marketplace, while design-restrictive rules tend to freeze technology, stifle research aimed at better and cheaper compliance measures, and deprive consumers of the opportunity to choose among competing designs. See S.Rep.No.92-835, 92d Cong., 2d Sess. 30 (1972), U.S.Code Cong. & Admin.News 1972, p. 4573; H.R. Rep.92-1153, 92d Cong., 2d Sess. 189 (1972).

Although only a limited number of designs can satisfy the blade-stop provision, we find this part of the standard is nonetheless a performance requirement. While the standard mandates that mower blades stop within a specified time period, it does not dictate a specific means of fulfilling this condition. Manufacturers are neither formally nor practically restricted to employing a particular design, since two existing mechanisms, a blade-disengagement system employing a brake-clutch device and an engine-stop system, are capable of passing the blade-stop test. See, e. g., D. D. Bean, 574 F.2d at 652. Moreover, the existence of many different designs for brake-clutch apparatus preserves manufacturer discretion in building mowers. And manufacturers remain free to develop new forms of technology that will meet the blade-stop criterion. The statutory direction that safety standards are to be framed as performance requirements when feasible does not mean that the Commission must develop standards that are so general that they can be' satisfied by every possible means for achieving an acceptable level of safety. Indeed, a performance requirement may be quite design restrictive in its practical import. See, e. g., Pacific Legal Foundation v. Department of Transportation, 593 F.2d 1338, 1340-41 & n.6 (D.C.Cir.), cert. denied, 444 U.S. 830, 100 S.Ct. 57, 62 L.Ed.2d 38 (1979) (upholding, under National Traffic & Motor Vehicle Safety Act of 1966, safety requirement that court characterized as “performance standard” and that could be satisfied by only two currently available systems, automatic passive seat belts and air bags); Paccar, Inc. v. National Highway Traffic Safety Administration, 573 F.2d 632, 639 & n.26 (9th Cir.), cert. denied, 439 U.S. 862, 99 S.Ct. 184, 58 L.Ed.2d 172 (1978) (evaluating “performance requirement” issued under NTMVSA that as a practical matter required employment of a particular device). Chrysler Corp. v. Department of Transportation, 472 F.2d 659, 664 & n.4 (6th Cir. 1972) (holding that performance requirement could establish minimum conditions that could be met by few systems since industry not foreclosed from develop