NHTSA Interpretation File Search
Overview
NHTSA's Chief Counsel interprets the statutes that the agency administers and the standards and regulations that it issues. Members of the public may submit requests for interpretation, and the Chief Counsel will respond with a letter of interpretation. These interpretation letters look at the particular facts presented in the question and explain the agency’s opinion on how the law applies given those facts. These letters of interpretation are guidance documents. They do not have the force and effect of law and are not meant to bind the public in any way. They are intended only to provide information to the public regarding existing requirements under the law or agency policies.
Understanding NHTSA’s Online Interpretation Files
NHTSA makes its letters of interpretation available to the public on this webpage.
An interpretation letter represents the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. While these letters may be helpful in determining how the agency might answer a question that another person has if that question is similar to a previously considered question, do not assume that a prior interpretation will necessarily apply to your situation.
- Your facts may be sufficiently different from those presented in prior interpretations, such that the agency's answer to you might be different from the answer in the prior interpretation letter;
- Your situation may be completely new to the agency and not addressed in an existing interpretation letter;
- The agency's safety standards or regulations may have changed since the prior interpretation letter was written so that the agency's prior interpretation no longer applies; or
- Some combination of the above, or other, factors.
Searching NHTSA’s Online Interpretation Files
Before beginning a search, it’s important to understand how this online search works. Below we provide some examples of searches you can run. In some cases, the search results may include words similar to what you searched because it utilizes a fuzzy search algorithm.
Single word search
Example: car
Result: Any document containing that word.
Multiple word search
Example: car seat requirements
Result: Any document containing any of these words.
Connector word search
Example: car AND seat AND requirements
Result: Any document containing all of these words.
Note: Search operators such as AND or OR must be in all capital letters.
Phrase in double quotes
Example: "headlamp function"
Result: Any document with that phrase.
Conjunctive search
Example: functionally AND minima
Result: Any document with both of those words.
Wildcard
Example: headl*
Result: Any document with a word beginning with those letters (e.g., headlamp, headlight, headlamps).
Example: no*compl*
Result: Any document beginning with the letters “no” followed by the letters “compl” (e.g., noncompliance, non-complying).
Not
Example: headlamp NOT crash
Result: Any document containing the word “headlamp” and not the word “crash.”
Complex searches
You can combine search operators to write more targeted searches.
Note: The database does not currently support phrase searches with wildcards (e.g., “make* inoperative”).
Example: Headl* AND (supplement* OR auxiliary OR impair*)
Result: Any document containing words that are variants of “headlamp” (headlamp, headlights, etc.) and also containing a variant of “supplement” (supplement, supplemental, etc.) or “impair” (impair, impairment, etc.) or the word “auxiliary.”
Search Tool
NHTSA's Interpretation Files Search
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ID: aiam5330OpenMr. Derrick Barker John Martin Designs 1 Clifton St. Stourbridge, West Midlands DY8 3XR; Mr. Derrick Barker John Martin Designs 1 Clifton St. Stourbridge West Midlands DY8 3XR; Dear Mr. Barker: This responds to your letter concerning the buckl release requirement of Federal Motor Vehicle Safety Standard No. 213, 'Child Restraint Systems.' I apologize for the delay in responding. You asked for the 'tensile load requirements for the buckle and tongue.' There is no specific requirement in Standard 213 for the tensile force that a child restraint buckle must withstand. Instead, the buckle must maintain its integrity when the child restraint is subjected to a simulated frontal impact at 30 mph with either a six-month-old (17 pounds (lbs.)) or three-year-old (33 lbs.) sized dummy restrained in the car seat. At the conclusion of the simulated impact, the force required to depress the latch button to release the buckle is measured and must be 16 lbs. or less. You also asked for a copy of Procedure D of the American Society for Testing and Materials Standard D756-78. Section S5.4.2 of FMVSS No. 213 sets forth those requirements by making reference to section S4.3(b) of FMVSS No. 209. which, in turn, leads to the reference to Procedure D of ASTM D756-78. The material you requested is enclosed. In addition, you asked for a list of laboratories that test child safety seats and buckles. NHTSA does not endorse particular test laboratories. However, I can provide you with a list of laboratories we are aware of that conduct child restraint compliance tests. There may be other laboratories that can test child safety seats and buckles. Please contact Ms. Deirdre Fujita of my staff if you have further questions. Sincerely, John Womack Acting Chief Counsel Enclosures; |
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ID: aiam0132OpenMr. J.B.H. Knight, Chief, Development and Car Safety Engineer, Rolls-Royce Limited, Motor Car Division, Pym's Lane, Crewe, Cheshire, England; Mr. J.B.H. Knight Chief Development and Car Safety Engineer Rolls-Royce Limited Motor Car Division Pym's Lane Crewe Cheshire England; Dear Mr. Knight: Thank you for your letter of November 8, 1968, requesting clarification of the 30g horizontal inertia load direction specified in Standard No. 201, as published in the *Federal Register* on October 25, 1968.; In section S3.3.1(c), 'Subject the interior compartment door latc system to a horizontal inertia load of 30g in a longitudinal direction...' means both forward and rearward directions. In addition, the loads specified in S3.3.1(a) are applied in both the inboard and outboard and the up and down directions. This is consistent with similar type requirements in Standard No. 206.; You state that a forward and rearward 30g inertia load requirement i more stringent than the alternative procedure of S3.3.1(b), the barrier test. The Bureau believes, and one large manufacturer so stated in his comments, that the most meaningful test of the ability of an interior compartment door to remain closed is one which considers the distortion an deformation loads that occur in a collision. A barrier or equivalent dynamic test is the best way of realistically evaluating the ability of these doors to remain closed. The bureau, therefore, believes that the barrier test is as stringent a requirement as S3.3.1(c).; Sincerely, William Haddon, Jr., M.D., Director |
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ID: aiam1689OpenMr. Curtis Eddy, Vice President - Engineering, Matlock Truck Body and Trailer Corporation, P. O. Box 7385, Nashville, TN 37210; Mr. Curtis Eddy Vice President - Engineering Matlock Truck Body and Trailer Corporation P. O. Box 7385 Nashville TN 37210; Dear Mr. Eddy: This is in reference to your defect notification campaign (NHTSA No 74-0203) concerning trailers equipped with Standard Forge axles which may have defective brake shoes.; The letter which you have sent to the owners of the subject trailer does not completely meet the requirements of Part 577(49 CFR), the Defect Notification regulation. Specifically, the second sentence of your letter describes the defect as existing in the brake shoes. Part 577.4(b), however, requires that in cases where a vehicle manufacturer is notifying owners of vehicles, the letter must state that a defect exists in the vehicle itself. The reference to motor vehicle equipment applies only to equipment campaigns where vehicles are not directly involved. Your letter also fails to adequately evaluate the risk to traffic safety as required by Part 577.4(d) since it does not state that the vehicle crash without warning may occur. Although the statement that reduced braking power or lockup may result may suggest the possibility of a crash to many owners, it is not entirely adequate.; Although mailing of a revised notification letter will not be required it is expected that in the event that another defect notification campaign ever becomes necessary in the future, the notification letters conform completely with the regulations.; A copy of Part 577 is enclosed. If you desire further information please contact Messrs. W. Reinhart or James Murray of this office at (202) 426- 2840.; Sincerely, Andrew G. Detrick, Acting Director, Office of Defect Investigation, Motor Vehicle Programs; |
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ID: aiam4171OpenFrederick B. Locker, Esq., Locker Greenberg & Brainin, P.C., One Penn Plaza, New York, NY 10001; Frederick B. Locker Esq. Locker Greenberg & Brainin P.C. One Penn Plaza New York NY 10001; Dear Mr. Locker: This responds to your June 4, 1986 letter to Mr. Francis Armstrong, th former Director of this agency's Office of Vehicle Safety Compliance. In that letter, you referred to the preliminary compliance test data sheet showing that the Kolcraft 'Flip N Go' booster seat failed to comply with section S5.2.4 of Standard No. 213, *Child Restraint Systems* (49 CFR S571.213). You stated that this preliminary noncompliance finding was based on a misinterpretation and misapplication of section S5.2.4. I conclude that Mr. Armstrong was acting on a correct interpretation of that section and properly applied it to the Kolcraft 'Flip N Go' booster seat.; For your information, section S5.2.4 reads as follows: >>>*Protrusion limitation*. Any portion of a rigid structural componen within or underlying a contactable surface, or any portion of a child restraint system surface that is subject to the requirements of S5.2.3 shall, with any padding or other flexible overlay material removed, have a height above any immediately adjacent restraint system surface of not more than 3/8 inch and no exposed edge with a radius of less than 1/4 inch.<<<; You asserted that S5.2.4 does not apply to the 'Flip N Go' Seat. As yo read S5.2.4, it applies only to child restraint systems that are also subject to S5.2.3. You note that the 'Flip N Go' seat is not recommended for children weighing less than 20 pounds, so the requirements of S5.2.3 are not applicable to it. You then conclude that the requirements of S5.2.4 should also not be applicable to that seat.; Your assertion is, however, based upon the misplacing of the firs comma in your quotation of S5.2.4. As S5.2.4 was quoted in your letter, the comma appeared as follows 'restraint system surface, that is subject.' In fact, there is no comma in that location. One does appear earlier: 'contactable surface, or any portion.' As you see from the correct version of S5.2.4 set forth above, it applies to both--; >>>(1) any portion of a rigid structural component within or underlyin a contactable surface, *AND; (2) any portion of a child restraint system surface that is subject t the requirements of S5.2.3.<<<; Since we both agree that the 'Flip N Go' seat is not subject to th requirements of S5.2.3, the question is whether all portions of its rigid structural components within or underlying a contactable surface satisfy the requirements of S5.2.4. Section S4 of Standard No. 213 defines a 'contactable surface' as 'any child restraint system surface (other than that of a belt, belt buckle, or belt adjustment hardware that may contact any part of the head or torso of the appropriate test dummy, specified in S7, when a child restraint system is tested in accordance with S6.1.' The preliminary compliance test data sheet for the 'Flip N Go' seat indicates that four different surfaces on the shield and shield support arms appear to fail to comply with the requirements of S5.2.4.; The first surface listed as not appearing to comply with S5.2.4 was th horizontal upper-forward edge of the shield, which has a radius of less than 1/4 inch. Your response is that this surface is not capable of being contacted by the child's head or neck. We disagree with you. However, even if the test dummy's head and neck failed to contact this edge, the dummy's torso *would* contact that surface. The torso contact would make the edge a contactable surface under S5.2.4, which prohibits the edge from having a radius of less than 1/4 inch. Accordingly, this edge does not appear to comply with S5.2.4, regardless of whether it is contacted by a child's head, neck, or torso.; The outboard left and right vertical edges of the shield support arm appear not to comply with two requirements of S5.2.4. First, the edges have radii of less than 1/4 inch. Second, the edges protrude more than 3/8 inch above the immediately adjacent shield surface. Your response to this was that the entire shield surface is integral and must be considered as a whole. When consider in this way, you stated that the edges of the shield support arms comply with S5.2.4. We cannot agree with your interpretation.; There is no basis in Standard No. 213 for your position that 'integral shields are considered as a whole for the purposes of S5.2.4. The only question under S5.2.4 is whether a contactable surface incorporates projections or narrow edges that could subject the child occupant to pressure point loading in the event of a crash. If the contactable surface incorporates such projections or narrow edges, it does not comply with S5.2.4. Since the edges of the shield support arms on the 'Flip N Go' seat are contactable surfaces which incorporate projections and have edge radii that are prohibited by S5.2.4, the edges of the shield support arms do not appear to comply with S5.2.4.; The third surfaces noted as not appearing to comply with S5.2.4 wer the inboard vertical surfaces of the shield support arms, because those surfaces have edges with radii of less than 1/4 inch. Your response to this was to repeat your integral shield argument and to state that Standard No. 213 does not require oblique crash simulations. This latter point was in response to the following statement in the preliminary compliance test data report: 'These edges and those described in (2) above could be contacted by the occupant in oblique crashes.'; This statement is not the reason for the preliminary determination tha those edges do not comply with S5.2.4 of Standard No. 213. It was included only to point out the actual safety hazard that could be presented to occupants of the 'Flip N Go' seat in a crash. The reason for the preliminary determination is that these edges appear to be contactable surfaces within the meaning of S4, and the edges have radii of less than 1/4 inch. I apologize for any confusion the statement about oblique crashes may have caused.; The fourth surface noted as not appearing to comply with S5.2.4 was th extreme bottom horizontal surface of the shield, with a radius of less than 1/4 inch. Additionally, that surface is supported by seven smaller vertical ribs, five of which are contactable and have edge radii of less than 1/4 inch. The data sheet concluded, 'All of these edges may be contacted by the occupant's thighs or lower abdomen.'; You responded to this by repeating your integral shield argument, an stating that the requirements of S5.2.4 are applicable only to situations involving head impact protection. Accordingly, you stated that S5.2.4 was not intended to address contact with the shield by an occupant's thighs or lower abdomen.; As noted above, section S5.2.4 requires all portions of the shiel within or underlying a 'contactable surface' to have no protrusions. A contactable surface refers to portions of the restraint that may contact any part of the head or *torso*. Section S4 of Standard No. 213 defines the term 'torso' as 'the portion of the body of a seated anthropomorphic test dummy, excluding the thighs, that lies between the top of the child restraint seating surface and the top of the shoulders of the test dummy.' Thus, the thighs would not be considered part of the torso, but the lower abdomen would. Section S5.2.4 is intended to prevent or reduce injuries to the torso, including the lower abdomen. Thus, any edge contactable by the test dummy's lower abdomen must have a radius of at least 1/4 inch to comply with S5.2.4. Since these edges have smaller radii, they do not appear to comply with that section.; Please contact our Office of Vehicle Safety Compliance if you have an further responses or comments on the preliminary noncompliance determination.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1373OpenLewis S. Hollins, Esq., Attorney at Law, One Chester Drive, Great Neck, NY 11021; Lewis S. Hollins Esq. Attorney at Law One Chester Drive Great Neck NY 11021; Dear Mr. Hollins: Dr. Gregory has asked me to respond to your client's request fo approval of the 'Hollins system' interlock device. In an earlier version, the system was the basis of a petition for an alternative to Standard 208's seatbelt interlock system. That petition was denied by the NHTSA (38 FR 9830, April 20, 1973, and 38 FR 16072, June 20, 1973) as was a petition for reconsideration of our decision (38 FR 33110, November 30, 1973).; Standard 208 establishes performance requirements, but the NHTSA doe not approve or disapprove specific equipment designs. Any design can be used to satisfy Standard 208 which fulfills the performance requirements. We have considered Mr. Hollins' proposal and, as set our (sic) in the *Federal Register*, have determined that his requested changes to the performance requirements are not justified. We feel that our consideration of Mr. Hollins' petition has been full and complete, and that further petitions on this subject will be repetitious within the meaning of 49 CFR S553.35(c).; Sincerely, Lawrence R. Schneider, Chief Counsel |
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ID: aiam3786OpenMr. Richard McCarl, American Isuzu Motors Inc., Whittier, CA 90601; Mr. Richard McCarl American Isuzu Motors Inc. Whittier CA 90601; Dear Mr. McCarl: This responds to your November 23, 1983 letter regarding th applicability of motor vehicle certification requirements to a new vehicle to be imported by Isuzu Motors. This small utility vehicle would be certified as a truck. Isuzu dealers will offer for the vehicle an optional rear seat which can be installed by simply bolting it to the vehicle. The basic vehicle already has the necessary mountings for the seat, so the seat installation can apparently be readily accomplished. You have asked whether installation of these seats constitutes 'alteration' of the vehicle by the dealer, requiring the addition of an alterer's label in accordance with 49 CFR 567.7.; Based on your description of the seat installation process, it appear that dealers installing the seats would be subject to 49 CFR 567.6, 'Requirements for persons who do not alter certified vehicles or do so with readily attachable components.' Since the seats appear to be 'readily attachable components,' section 567.6 requires dealers to leave the manufacturer's certification label in place and requires no alterer's label to be added.; If you have further questions on this matter, please contact us. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4043OpenMr. Roger F. Hagie, Government Relations Manager, Kawasaki Motors Corporation, U.S.A., P. O. Box 11447, Santa Ana, CA 92711; Mr. Roger F. Hagie Government Relations Manager Kawasaki Motors Corporation U.S.A. P. O. Box 11447 Santa Ana CA 92711; Dear Mr. Hagie: This responds to your April 11, 1986, letter to this office requestin an interpretation of Federal Motor Vehicle Safety Standard (FMVSS) No. 106, *Brake Hoses*. We regret the delay in our response; You asked whether brake hoses that comply with all requirements o Standard No. 106 except the whip resistance test of S5.3.3 may be used in locations not subject to movement during vehicle operation. As explained below, the answer to your question is no.; As you know, Standard No. 106 defines 'brake hose' as 'a flexibl conduit, other than a vacuum tubing connector, manufactured for use in a brake system to transmit or contain the fluid pressure or vacuum used to apply force to a vehicle's brakes.' Manufacturers of brake hoses must certify that their hoses comply with all applicable requirements of the standard. From your letter, it appears that while you agree that the equipment you manufacture are brake hoses, you believe that they should not be subject to whip resistance test because your hoses would not be used between articulating parts.; We do not agree that the whip test does not apply to brake hoses use between non- articulating parts. No provision has been made in the standard or in the whip resistance test of S5.3.3 to exclude hoses manufactured for use between non-moving parts. In contrast, the standard has set separate requirements under certain tests for brake hoses used between articulating parts when it is appropriate to distinguish between articulating and non-articulating applications (see, for example, the tensile strength test of S7.3.10 for air brake hose assemblies).; Further, we believe that there is a safety need to test brake hose intended for non-articulating applications for fatigue resistance, since they are also subject to vibration, bending and articulating stress while the motor vehicle is being operated or repaired.; If you have further questions, please let me know. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1241OpenMr. David E. Martin, Manager, Automotive Safety Engineering, Environmental Activities Staff, General Motors Technical Center, General Motors Corporation, Warren, MI 48090; Mr. David E. Martin Manager Automotive Safety Engineering Environmental Activities Staff General Motors Technical Center General Motors Corporation Warren MI 48090; Dear Mr. Martin: Dr. Gregory has asked me to reply to your letter of August 28, 1973, i which you request our endorsement of new labels General Motors intends to use to fulfill its responsibilities under part 567 of Title 49 of the Code of Federal Regulations.; The wording on the label meets the requirements of paragraph 567.4(g) The color of the paint under the label 'window' would determine conformity with the contrasting color requirements in paragraph 567.4(f).; It would appear that the material would '. . .be permanently affixed. .' if it '. . .is tightly bonded to the surface of the vehicle panel. . . .' However, it has not been the practice of the National Highway Traffic Safety Administration to endorse label materials.; Thank you for your continuing cooperation. Sincerely, Robert L. Carter |
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ID: aiam0846OpenMr. R. A. C. Dandy, Senior Engineer, Head of Mechanical Section, British Standards Institution, Hemel Hempstead Centre, Maylands Avenue, Hemel Hempstead, Herts, England; Mr. R. A. C. Dandy Senior Engineer Head of Mechanical Section British Standards Institution Hemel Hempstead Centre Maylands Avenue Hemel Hempstead Herts England; Dear Mr. Dandy: This is in further reply to your letter of July 26, 1972, concernin the seat belt retractor test procedures of section S5.2(k) of Motor Vehicle Safety Standard No. 209.; In our initial reply of August 21, we stated that the belt was to b retracted completely during the cycling, even though some vehicle installations might prevent complete retraction. After further examining the consequences of this position, we have concluded that it is in error.; The intent of the cycling sequence is to reflect the normal use of th belt over time. If the belt is designed to be installed in a vehicle in such a manner that during normal cycling a part of the webbing cannot be wound onto the retractor, a compliance test should employ the same restrictions of movement. We therefore conclude that you are correct in considering a belt to be fully retracted for purposes of Standard No. 209 when it is retracted as fully as the geometry of its installation permits.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1754OpenMr. William J. Flanagan, Executive Director, New Jersey Turnpike Authority, New Brunswick, NJ 08903; Mr. William J. Flanagan Executive Director New Jersey Turnpike Authority New Brunswick NJ 08903; Dear Mr. Flanagan: This is in reply to your letter of December 3, 1974, requesting ou view whether the removal of portions of a tie bar in a truck tire, for the purpose of reducing tire noise, is subject to NHTSA's *Regrooved Tire* regulation (49 CFR Part 569). You state that the removal of the tie bar material does not require that the tread be cut to a depth equal to or deeper than the original groove depth.; We concur in your opinion that the partial removal of tire tie ba material is not subject to the *Regrooved Tire* regulations. This practice would not be considered the making of a 'regrooved tire' (49 CFR S 569.3(d)) as long as the removal of tie bar material did not extend to the original tread depth. Any removal or renewal of tread that did extend to at least the original tread depth, however, would be considered the making of a 'regrooved tire' and would be subject to the requirements set forth in S 569.7 of the regulation.; We are concerned, however, that this opinion may result in th indiscriminate removal of tire tie bar material from truck tires having varying tread designs. We believe it possible, notwithstanding the absence of regulations prohibiting such removal, that the removal of tie bar material could in some cases induce tread cracking, instability, and otherwise reduce the safe performance of truck tires. Consequently, we believe you should determine, through testing if necessary, that removal of tire tie bar material will not produce adverse results in tire performance before any large-scale project involving venting is implemented. Any such program should also take into account that effects of venting may differ among various tread designs. Finally, tread venting on new tires manufactured after March 1, 1975, could affect the conformity of those tires to Federal Motor Vehicle Safety Standard No. 119.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.