Editing Headlamp (section)

== Regulations and requirements ==
Modern headlamps are electrically operated, positioned in pairs, one or two on each side of the front of a vehicle. A headlamp system is required to produce a low and a high beam, which may be produced by multiple pairs of single-beam lamps or by a pair of dual-beam lamps, or a mix of single-beam and dual-beam lamps.<ref>{{Cite web |last=Wade |first=David |date=2025-01-31 |title=The LED headlight debate: Safer or too bright? Europe has a smarter option |url=https://www.centraloregondaily.com/news/consumer/the-led-headlight-debate-safer-or-too-bright-europe-has-a-smarter-option/article_4de7c9f6-e010-11ef-b471-87d2461b22f5.html |access-date=2025-02-05 |website=Central Oregon Daily |language=en}}</ref> High beams cast most of their light straight ahead, maximizing seeing distance but producing too much [[glare (vision)|glare]] for safe use when other vehicles are present on the road. Because there is no special control of upward light, high beams also cause backdazzle from [[fog]], rain and snow due to the [[retroreflection]] of the water [[droplet]]s. Low beams have stricter control of upward light, and direct most of their light downward and either rightward (in right-traffic countries) or leftward (in left-traffic countries), to provide forward visibility without excessive glare or backdazzle.

=== Low beam ===
{{Redirect|Low Beam|the 2018 Her's song|Invitation to Her's}}
{| style="float:right;"
|-
|[[File:2005 winter road dipped beam.jpg|thumb|ECE dipped/low beam]]
|[[File:Low beam light pattern for right-hand traffic.svg|thumb|Asymmetrical low beam illumination of road surface – [[Right- and left-hand traffic|right-traffic]] beam shown]]
|}

Low beam (dipped beam, passing beam, meeting beam) headlamps provide a distribution of light designed to provide forward and lateral illumination, with limits on light directed towards the eyes of other road users to control glare. This beam is intended for use whenever other vehicles are present ahead, whether oncoming or being overtaken.

The international [[ECE Regulations]] for [[#Tungsten-halogen light sources|filament headlamps]]<ref>{{cite web|url= https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2013/R112r3e.pdf |title=UN Regulation 112 }}&nbsp;{{small|(313&nbsp;KB)}}</ref> and for [[High-intensity discharge lamp|high-intensity discharge headlamps]]<ref>{{cite web|url= http://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/R098r3e.pdf |title=UN Regulation 98 }}&nbsp;{{small|(843&nbsp;KB)}}</ref> specify a beam with a sharp, asymmetric cutoff preventing significant amounts of light from being cast into the eyes of drivers of preceding or oncoming cars. Control of glare is less strict in the North American [[Society of Automotive Engineers|SAE]] beam standard contained in [[Federal Motor Vehicle Safety Standard 108|FMVSS / CMVSS 108]].<ref>{{cite web|url= http://a257.g.akamaitech.net/7/257/2422/12feb20041500/edocket.access.gpo.gov/cfr_2004/octqtr/pdf/49cfr571.108.pdf |title=FMVSS No. 108 }}&nbsp;{{small|(2.00&nbsp;MB)}}</ref>

{{clear}}

=== High beam ===
{{Redirect2|High beam|High beams|other uses|High beam (disambiguation)}} 
{| style="float:right;"
|-
|[[File:2005 winter road full beam.jpg|thumb|ECE high/main beam]]
|[[File:Phare route.png|thumb|Symmetrical high beam illumination of road surface]]
|}

High beam (main beam, driving beam, full beam) headlamps provide a bright, center-weighted distribution of light with no particular control of light directed towards other road users' eyes. As such, they are only suitable for use when alone on the road, as the glare they produce will dazzle other drivers.

International [[ECE Regulations]] permit higher-intensity high-beam headlamps than are allowed under [[Federal Motor Vehicle Safety Standard 108|North American regulations]].<ref>{{cite book|first=Kåre |last=Rumar|title=Relative merits of the U.S. and ECE high-beam maximum intensities and of two- and four-headlamp systems |year=2000|publisher=UMTRI |hdl=2027.42/49438}}</ref>

=== Compatibility with traffic directionality ===
{{see also|Right- and left-hand traffic}}
[[File:Dagen H Headlamp.jpg|thumb|right|200px|Headlamp sold in Sweden not long before [[Dagen H]] changeover from left to right hand traffic. Opaque decal blocks the lens portion for low beam upkick to the right, and bears the warning: "Not to be removed before 3 September 1967".]]

Most low-beam headlamps are specifically designed for use on [[Traffic directionality|only one side of the road]]. Headlamps for use in left-traffic countries have low-beam headlamps that "dip to the left"; the light is distributed with a downward/leftward bias to show the driver the road and signs ahead without blinding oncoming traffic. Headlamps for right-traffic countries have low beams that "dip to the right", with most of their light directed downward/rightward.

Within Europe, when driving a vehicle with right-traffic headlamps in a left-traffic country or vice versa for a limited time (as for example on vacation or in transit), it is a legal requirement to adjust the headlamps temporarily so that their wrong-side beam distribution does not dazzle oncoming drivers. This may be achieved by methods including adhering opaque decals or prismatic lenses to a designated part of the lens. Some projector-type headlamps can be made to produce a proper left- or right-traffic beam by shifting a lever or other movable element in or on the lamp assembly.<ref>{{cite web|url= http://pages.citebite.com/p4a2w8a1ojrn |title=Driving Abroad: Headlights |publisher=UK Automobile Association |date=1 August 2012 |access-date=29 May 2014}}</ref> Many tungsten (pre-halogen) European-code headlamps made in France by Cibié, Marchal, and Ducellier could be adjusted to produce either a left- or a right-traffic low beam by means of a two-position bulb holder.

Because wrong-side-of-road headlamps blind oncoming drivers and do not adequately light the driver's way, and blackout strips and adhesive prismatic lenses reduce the safety performance of the headlamps, some countries require all vehicles registered or used on a permanent or semi-permanent basis within the country to be equipped with headlamps designed for the correct traffic-handedness.<ref>{{Cite web|url=http://bfgnet.de/advice/vlo/change-to-headlights-requirements.html|title=BFG: Headlights}}</ref><ref>{{Cite web|url=http://www.arrse.co.uk/community/threads/changes-to-vehicle-headlight-policy.67707/|title=Changes to vehicle headlight policy. &#124; Army Rumour Service|date=11 September 2007 }}</ref> North American vehicle owners sometimes privately import and install [[Japanese domestic market|Japanese-market (JDM)]] headlamps on their car in the mistaken belief that the beam performance will be better, when in fact such misapplication is quite hazardous and illegal.<ref>{{cite web|url= http://www.danielsternlighting.com/tech/lights/codes/codes.html#Dip |title=Headlamp traffic-handedness |website=Danielsternlighting.com |date=2008-01-28 |access-date=2010-12-29}}</ref><ref>{{Cite web|url=http://drivesmartbc.ca/miscellaneous/right-hand-drive-vehicles-left-hand-drive-world|title=Right Hand Drive Vehicles in a Left Hand Drive World &#124; DriveSmartBC|website=drivesmartbc.ca}}</ref>

=== Adequacy ===
Vehicle headlamps have been found unable to illuminate an [[assured clear distance ahead]] at speeds above 60&nbsp;km/h (40&nbsp;mph).<ref name="AAA headlights">{{cite news |last1=McKernan |first1=Megan |title=AAA Tests Shine High-Beam on Headlight Limitations |url= https://newsroom.aaa.com/2015/05/aaa-tests-shine-high-beam-headlight-limitations/ |access-date=3 July 2018 |agency=AAA Automotive Research Center |website=NewsRoom.AAA.com |date=13 May 2015 |quote=AAA’s test results suggest that [[#Tungsten-halogen|halogen headlights]], found in over 80 percent of vehicles on the road today, may fail to '''safely''' illuminate unlit roadways at speeds as low as 40 mph. ...high-beam settings on halogen headlights...'''may only provide enough light to safely stop at speeds of up to 48 mph''', leaving drivers vulnerable at highway speeds...Additional testing found that while the advanced headlight technology found in [[#High-intensity discharge (HID)|HID]] and [[#LED|LED]] headlights illuminated dark roadways 25 percent further than their halogen counterparts, they still may fail to fully illuminate roadways at speeds greater than 45 mph. High-beam settings on these advanced headlights offered significant improvement over low-beam settings, lighting distances of up to 500 feet (equal to 55 mph). Despite the increase, '''even the most advanced headlights fall 60 percent short of the [[sight distance]] that the full light of day provides.'''}}</ref><ref name="NHTSA Night&Day">{{cite web |url=https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/810637 |title=Passenger Vehicle Occupant Fatalities by Day and Night – A Contrast |last1=Varghese |first1=Cherian |last2=Shankar |first2=Umesh |agency=National Center for Statistics and Analysis |publisher=National Highway Traffic Safety Administration |location=Washington, DC |date=May 2007 |quote=The passenger vehicle occupant fatality rate at nighttime is about three times higher than the daytime rate. ...'''The data shows a higher percentage of passenger vehicle occupants killed in speeding-related crashes at nighttime.'''}}</ref><ref name="Leibowitz&Herschel">{{cite journal |last1=Leibowitz |first1=Herschel W. |last2=Owens |first2=D. Alfred |last3=Tyrrell |first3= Richard A. |year=1998 |title=The assured clear distance ahead rule: implications for nighttime traffic safety and the law |journal=Accident Analysis & Prevention |volume=30 |issue=1 |pages=93–99 |doi=10.1016/S0001-4575(97)00067-5 |pmid=9542549 |quote=The assured clear distance ahead (ACDA) rule holds the operator of a motor vehicle responsible to avoid collision with any obstacle that might appear in the vehicle's path. Although widely considered a fundamental responsibility of safe driving, '''the ACDA rule is routinely violated by most drivers under nighttime conditions.'''}}</ref><ref name="236 Cal. App. 2d 555">{{cite court|litigants=Bove v. Beckman, 236 Cal. App. 2d 555|vol=236|reporter=Official California Appellate Reports|opinion=555|court=[[California courts of appeal|California Appellate Court]]|publisher=Bancroft-Whitney; LexisNexis |date=16 August 1965|url=http://law.justia.com/cases/california/calapp2d/236/555.html|access-date=2018-07-11|quote="A person driving an automobile at 65 miles an hour on a highway on a dark night with his lights on low beam affording a forward vision of only about 100 feet was driving at a negligent and excessive speed which was inconsistent with any right of way that he might otherwise have had." (CA Reports Official Headnote #[8])}} See [http://www.lexisnexis.com/clients/CACourts/ California Official Reports: Online Opinions]</ref><ref name="245 Mich. 88">{{cite court |litigants=Ruth v. Vroom, 245 Mich. 88, 222 N. W. 155, 62 A. L. R. 1528 |vol=245 |reporter=Mich. |opinion=88 |court=[[Supreme Court of Michigan]] |date=4 December 1928 |url=https://casetext.com/case/ruth-v-vroom |quote=It is settled in this State that it is negligence as a matter of law to drive an automobile at night at such speed that it cannot be stopped within the distance that objects can be seen ahead of it; and, if a driver's vision is obscured by the lights of an approaching car, it is his duty to slacken speed and have his car under such control that he can stop immediately if necessary. ... The rule adopted by this court does not raise merely a rebuttable presumption of negligence. It is a rule of safety. ... It is not enough that a driver be able to begin to stop within the range of his vision, or that he use diligence to stop after discerning an object. The rule makes no allowance for delay in action.}}</ref> It may be unsafe<ref name="AAA headlights"/> and, in a few areas, illegal<ref name="NY Jur">{{cite book |title=New York Jurisprudence |series=Automobiles and Other Vehicles |number=4A |page=§ 720 |author=Lawyers Cooperative Publishing |location=Miamisburg, OH |publisher=LEXIS Publishing |url=http://legalsolutions.thomsonreuters.com/law-products/Legal-Encyclopedias/New-York-Jurisprudence-2d/p/100029357 |oclc=321177421 |quote=It is negligence as a matter of law to drive a motor vehicle at such a rate of speed that it cannot be stopped in time to avoid an obstruction discernible within the driver's length of vision ahead of him. This rule is known generally as the 'assured clear distance ahead' rule * * * In application, the rule constantly changes as the motorist proceeds, and is measured at any moment by the distance between the motorist's vehicle and the limit of his vision ahead, or by the distance between the vehicle and any intermediate discernible static or forward-moving object in the street or highway ahead constituting an obstruction in his path. Such rule requires a motorist in the exercise of due care at all times to see, or to know from having seen, that the road is clear or apparently clear and safe for travel, a sufficient distance ahead to make it apparently safe to advance at the speed employed.}}</ref><ref name="232 Mich. 300">{{cite court |litigants=Gleason v. Lowe, 232 Mich. 300 |vol=232 |reporter=Mich. |opinion=300 |court=[[Supreme Court of Michigan]] |date=1 October 1925 |url=https://casetext.com/case/gleason-v-lowe |quote=...every man must operate his automobile so that he can stop it within the range of his vision, whether it be daylight or darkness. It makes no difference what may obscure his vision, whether it be a brick wall or the darkness of nightfall. ... He must ... be able to see where he is going, and if his range of vision is 50 feet, if he can see 50 feet ahead of him, he must regulate his speed so that he can stop in a distance of 50 feet; if he can see 20 feet ahead of him, he must regulate his speed so that he can stop within 20 feet, and so on.}}</ref><ref name="235 N.C. 568">{{cite court |litigants=Morris v. Jenrette Transport Co. |vol=235 |reporter=N.C. |opinion=568 |court=[[Supreme Court of North Carolina]] |date=21 May 1952 |url=http://law.justia.com/cases/north-carolina/supreme-court/1952/451-2-1.html |access-date=February 2016 |quote=It is not enough that the driver of plaintiff's automobile be able to begin to stop within the range of his lights, or that he exercise due diligence after seeing defendants' truck on the highway. He should have so driven that he could and would discover it, perform the manual acts necessary to stop, and bring the automobile to a complete stop within the range of his lights. When blinded by the lights of the oncoming car so that he could not see the required distance ahead, it was the duty of the driver within such distance from the point of blinding to bring his automobile to such control that he could stop immediately, and if he could not then see, he should have stopped. In failing to so drive he was guilty of negligence which patently caused or contributed to the collision with defendants' truck, resulting in injury to plaintiff."...it was his duty to anticipate presence of others, [...] and hazards of the road, such as disabled vehicle, and, in the exercise of due care, to keep his automobile under such control as to be able to stop within the range of his lights}}</ref> to drive above this speed at night.

=== Use in daytime ===
{{Main|Daytime running lamp}}
Some countries require automobiles to be equipped with [[daytime running lamp|daytime running lights]] (DRL) to increase the [[wikt:conspicuity|conspicuity]] of vehicles in motion during the daytime. Regional regulations govern how the DRL function may be provided. In Canada, the DRL function required on vehicles made or imported since 1990 can be provided by the headlamps, the [[fog lamp]]s, steady-lit operation of the front [[turn signal]]s, or by special daytime running lamps.<ref>{{Cite web|url=http://www.tc.gc.ca/eng/acts-regulations/regulations-crc-c1038-sch-iv-108.htm|title=Lighting System and Retroreflective Devices (Standard 108) - Transport Canada|date=21 June 2013|archive-url=https://web.archive.org/web/20130621034916/http://www.tc.gc.ca/eng/acts-regulations/regulations-crc-c1038-sch-iv-108.htm |archive-date=21 June 2013 }}</ref> Functionally dedicated daytime running lamps not involving the headlamps are required on all new cars first sold in the [[European Union]] since February 2011.<ref>{{cite press release|url= http://europa.eu/rapid/pressReleasesAction.do?reference=IP/11/133&type=HTML |title=New cars equipped with daytime running lights as of today |website=Europa.eu |date=13 May 2014 |access-date=29 May 2014}}</ref> In addition to the EU and Canada, countries requiring DRL include Albania, Argentina,<ref>{{cite news |title=Ya es ley el uso obligatorio de las luces bajas para circular de día |newspaper=Clarín |date=9 August 2001 |url= http://www.clarin.com/diario/2001/08/09/s-03801.htm |language=es |access-date=29 May 2014}}</ref> Bosnia and Herzegovina, Colombia (no more from Aug/2011), Iceland, Israel, Macedonia, Norway, Moldova, Russia, Serbia, and Uruguay.{{Citation needed|date=July 2012}}

=== Construction, performance, and aim ===
There are two different beam pattern and headlamp construction standards in use in the world: The [[World Forum for Harmonization of Vehicle Regulations|ECE]] standard, which is allowed or required in virtually all industrialized countries except the United States, and the [[Society of Automotive Engineers|SAE]] [[Federal Motor Vehicle Safety Standard 108|standard]] that is mandatory only in the US. Japan formerly had bespoke lighting regulations similar to the US standards, but for the left side of the road. However, Japan now adheres to the ECE standard. The differences between the SAE and ECE headlamp standards are primarily in the amount of glare permitted toward other drivers on low beam (SAE permits much more glare), the minimum amount of light required to be thrown straight down the road (SAE requires more), and the specific locations within the beam at which minimum and maximum light levels are specified.

ECE low beams are characterized by a distinct horizontal "cutoff" line at the top of the beam. Below the line is bright, and above is dark. On the side of the beam facing away from oncoming traffic (right in right-traffic countries, left in left-traffic countries), this cutoff sweeps or steps upward to direct light to road signs and pedestrians. SAE low beams may or may not have a cutoff, and if a cutoff is present, it may be of two different general types: ''VOL'', which is conceptually similar to the ECE beam in that the cutoff is located at the top of the left side of the beam and aimed slightly below horizontal, or ''VOR'', which has the cutoff at the top of the right side of the beam and aimed at the horizon.<ref name="WDTGCF">{{cite web |url= http://dmses.dot.gov/docimages/pdf82/176157_web.pdf |title= "Where Does The Glare Come From?" (NHTSA glare response + white paper on headlamp performance, glare, and regulation) |url-status= dead |archive-url= https://web.archive.org/web/20030803104147/http://dmses.dot.gov/docimages/pdf82/176157_web.pdf |archive-date= 3 August 2003}}&nbsp;{{small|(463&nbsp;KB)}}</ref>

Proponents of each headlamp system decry the other as inadequate and unsafe: US proponents of the SAE system claim that the ECE low beam cutoff gives short seeing distances and inadequate illumination for overhead road signs, while international proponents of the ECE system claim that the SAE system produces too much glare.<ref>{{cite web |last=Grueninger |first=Wes |title=Prometheus, Bound: The Difference Between American and European Car Lighting |website=MotiveMag.com |date=5 March 2008 |url= http://www.motivemag.com/pub/feature/tech/Motive_Tech_The_Difference_Between_US_and_European_Lights.shtml |access-date=29 May 2014 |url-status=dead |archive-url= https://web.archive.org/web/20090501102913/http://www.motivemag.com/pub/feature/tech/Motive_Tech_The_Difference_Between_US_and_European_Lights.shtml |archive-date=1 May 2009}}</ref> Comparative studies have repeatedly shown that there is little or no overall safety advantage to either SAE or ECE beams; the two systems' acceptance and rejection by various countries is based primarily on which system is already in use.<ref name="WDTGCF"/><ref name="Dayton">{{Cite web|url=https://www.regulations.gov/document/NHTSA-2001-8885-1508|title=Regulations.gov|website=www.regulations.gov}}</ref>

In North America, the design, performance, and installation of all [[Automotive lighting|motor vehicle lighting]] devices are regulated by [[Federal Motor Vehicle Safety Standard 108|Federal and Canada Motor Vehicle Safety Standard 108]], which incorporates [[Society of Automotive Engineers|SAE]] technical standards. Elsewhere in the world, ECE [[World Forum for Harmonization of Vehicle Regulations|internationalized regulations]] are in force either by reference or by incorporation in individual countries' vehicular codes.

US laws required [[sealed beam]] headlamps on all vehicles between 1940 and 1983, and other countries such as Japan, United Kingdom, and Australia also made extensive use of sealed beams.{{when|date=January 2014}} In most other countries, and in the US since 1984, replaceable-bulb headlamps predominate.

Headlamps must be kept in proper aim.<ref>{{cite web|url=http://www.searchautoparts.com/aftermarket-business/newsmaker/international-newsmaker-q-daniel-stern |first=James E. |last=Guyette |title=International Newsmaker Q&A: Daniel Stern |website=Searchautoparts.com |date=19 October 2012 |access-date=29 May 2014}}</ref> Regulations for aim vary from country to country and from beam specification to beam specification. In the US, SAE standard headlamps are aimed without regard to headlamp mounting height. This gives vehicles with high-mounted headlamps a seeing distance advantage, at the cost of increased glare to drivers in lower vehicles. By contrast, ECE headlamp aim angle is linked to headlamp mounting height, to give all vehicles roughly equal seeing distance and all drivers roughly equal glare.<ref name="aim">{{cite web|url= http://www.danielsternlighting.com/tech/aim/aim.html |title=Headlamp aiming specifications & procedures |website=Danielsternlighting.com |date=October 2012 |access-date=29 May 2014}}</ref>

==== Light colour ====
=====White=====
Headlamps are generally required to produce white light, according to both ECE and SAE standards. ECE Regulation 48 currently requires new vehicles to be equipped with headlamps emitting white light.<ref name="R48"/> Different headlamp technologies produce different characteristic types of white light; the white specification is quite large and permits a wide range of apparent colour from warm white (with a brown-orange-amber-yellow cast) to cold white (with a blue-violet cast).

===== Selective yellow =====
[[File:Kerkrade 2CV Front.jpg|thumb|upright|1957 [[Citroën 2CV]] with [[selective yellow]] headlamps and auxiliary lamp]]Previous ECE regulations also permitted [[selective yellow]] light. A research experiment done in the UK in 1968 using tungsten (non-halogen) lamps found that visual acuity is about 3% better with selective yellow headlamps than with white ones of equal intensity.<ref name=LR156>{{cite report |last1=Christie |first1=A.W. |last2=Ashwood |first2=J.E. |last3=Symons |first3=R.D.H. |year=1968 |title=Visual Acuity in Yellow Headlights |publisher=UK Ministry of Transport Road Research Laboratory |id=LR 156 |url=https://trl.co.uk/sites/default/files/LR156.pdf |archive-url=https://web.archive.org/web/20180729230449/https://trl.co.uk/sites/default/files/LR156.pdf |archive-date=2018-07-29 |access-date=29 July 2018}}</ref> Research done in the Netherlands in 1976 concluded that yellow and white headlamps are equivalent as regards traffic safety, though yellow light causes less discomfort glare than white light.<ref name=SWOV1976>{{cite report |year=1976 |title=White or Yellow Light for Vehicle Head-Lamps? |publisher=SWOV Institute for Road Safety Research |id=1976-2E |url=https://www.swov.nl/publicatie/white-or-yellow-light-vehicle-head-lamps |access-date=29 July 2018}}</ref> Researchers note that tungsten filament lamps emit only a small amount of the blue light blocked by a selective-yellow filter,<ref name=LR156/> so such filtration makes only a small difference in the characteristics of the light output,<ref name=Snow>{{cite journal|title=Driving in Snow: Effect of Headlamp Color at Mesopic and Photopic Light Levels|journal=SAE Technical Paper Series|year=2001|first1=John|last1=Bullough |first2=Mark S. |last2=Rea |volume=1 |doi=10.4271/2001-01-0320 |url= http://www.lightingresearch.org/programs/transportation/pdf/SAE/2001-01-0320.pdf|archive-url= https://web.archive.org/web/20060223111121/http://www.lightingresearch.org/programs/transportation/pdf/SAE/2001-01-0320.pdf|url-status=dead|archive-date=2006-02-23|access-date=2010-01-27}}</ref> and suggest that headlamps using newer kinds of sources such as metal halide (HID) bulbs may, through filtration, give off less visually distracting light while still having greater light output than halogen ones.<ref name=Snow/>

Selective yellow headlamps are no longer common, but are permitted in various countries throughout Europe{{vague|date=November 2014}} as well as in non-European locales such as South Korea, Japan<ref>[http://retail.ihs.com/abstracts/jsa/jis-d-5500.jsp Japanese Industrial Standard JIS D-5500] {{webarchive|url=https://web.archive.org/web/20070815142229/http://retail.ihs.com/abstracts/jsa/jis-d-5500.jsp |date=15 August 2007 }} ''Automobile Parts--Lighting and Light Signaling Devices'' p. 5, sec. 4.4.2, table #4</ref> and New Zealand.<ref>{{cite web|url=http://landtransport.govt.nz/certifiers/virm-in-service/general-v3.pdf |title=New Zealand Vehicle Inspection Requirement Manual p. 4.1.2 |website=Landtransport.govt.nz |access-date=2012-01-31}}</ref> In [[Iceland]], yellow headlamps are allowed<ref>[http://ww2.us.is/sw_documents/421 Icelandic Transport Authority US.321 Information on permitted headlight equipment on vehicles in Iceland.(46 KB)] {{webarchive|url=https://web.archive.org/web/20131203001807/http://ww2.us.is/sw_documents/421 |date=3 December 2013 }}''Information on allowed headlight equipment.'' Umferðastofa Íslands {{cite web |url=http://ww2.us.is/ |title=Umferðarstofa |access-date=2013-11-25 |url-status=dead |archive-url=https://web.archive.org/web/20131122103926/http://ww2.us.is/ |archive-date=22 November 2013}} Retrieved 2013-11-25.</ref> and the vehicle regulations in [[Monaco]] still officially require selective yellow light from all vehicles' low beam<ref>{{Cite web|url=http://www.legimonaco.mc/305/legismclois.nsf/Code/8F0D3ABE9EA3E9C6C125773F002D89D7!OpenDocument|title=LégiMonaco - Code De La Route - Article 76|date=3 March 2016|archive-url=https://web.archive.org/web/20160303220436/http://www.legimonaco.mc/305/legismclois.nsf/Code/8F0D3ABE9EA3E9C6C125773F002D89D7!OpenDocument |archive-date=3 March 2016 }}</ref> and high beam<ref>{{Cite web|url=http://www.legimonaco.mc/305/legismclois.nsf/Code/8D3FC42532ACB529C125773F002D89B2!OpenDocument|title=LégiMonaco - Code De La Route - Article 75|date=3 March 2016|archive-url=https://web.archive.org/web/20160303214939/http://www.legimonaco.mc/305/legismclois.nsf/Code/8D3FC42532ACB529C125773F002D89B2!OpenDocument |archive-date=3 March 2016 }}</ref> headlamps, and fog lamps if present.<ref>{{Cite web|url=https://www.legimonaco.mc/305/legismclois.nsf/Code/E048DCA0A9119957C125773F002D8B5E!OpenDocument|title=LégiMonaco - Code De La Route - Article 84|date=20 January 2021|archive-url=https://web.archive.org/web/20210120031600/https://www.legimonaco.mc/305/legismclois.nsf/Code/E048DCA0A9119957C125773F002D8B5E!OpenDocument |archive-date=20 January 2021 }}</ref>

In France, a statute passed in November 1936 based on advice from the Central Commission for Automobiles and for Traffic in General, required selective yellow headlights to be fitted.<ref>{{Cite web|url=https://gallica.bnf.fr/ark:/12148/bpt6k65489960|title=Journal officiel de la République française. Lois et décrets|date=5 November 1936|website=Gallica}}</ref> The mandate for yellow headlamps was enacted to reduce driver fatigue from [[Glare (vision)|discomfort glare]].<ref>{{cite journal |last1=Nelson |first1=J. H. |title=Automobile Headlamps |journal=Lighting Research and Technology |date=1 June 1957 |volume=22 |issue=6 IEStrans |pages=141–163 |doi=10.1177/147715355702200601 |bibcode=2014LR&T...46...20S |s2cid=112037485 }}</ref> The requirement initially applied to vehicles registered for road use after April 1937, but was intended to extend to all vehicles through retrofitting of selective yellow lights on older vehicles, from the start of 1939. Later stages of the implementation were disrupted in September 1939 by the outbreak of [[World War II|war]].{{Citation needed|date=November 2014}}

The French yellow-light mandate was based on observations by the [[French Academy of Sciences]] in 1934, when the academy recorded that the selective yellow light was less dazzling than white light and that the light diffused less in fog than green or blue lights.{{Citation needed|date=November 2014}} Yellow light was obtained by dint of yellow glass for the headlight bulb or lens, a yellow coating on a colourless bulb, lens, or reflector, or a yellow filter between the bulb and the lens.<ref>{{cite report |last1=Moore |first1=David W. |title=Headlamp History and Harmonization |publisher=Transportation Research Institute |date=June 1998|hdl=2027.42/49367 |hdl-access=free}}</ref> Filtration losses reduced the emitted light intensity by about 18 percent, which might have contributed to the reduced glare.<ref>{{cite journal|last=Jehu |first=V. J. |title=A comparison of yellow and white headlamp beams |journal=Light and Lighting |volume=47 |pages=287–291 |year=1954}}</ref>

The mandate was in effect until December 1992,<ref name="hearings-1993">{{cite book |author=United States Congress Senate Committee on Appropriations Subcommittee on Transportation and Related Agencies |title=Department of Transportation and Related Agencies Appropriations for Fiscal Year 1993: Hearings Before a Subcommittee of the Committee on Appropriations, United States Senate, One Hundred Second Congress, Second Session, on H.R. 5518 |year=1992 |publisher=U.S. Government Printing Office |isbn=9780160390456 |page=516 |url= https://books.google.com/books?id=HSoW4KdPMB4C&q=Headlamps+in+France+must+provide+yellow+light+while+white+is+required+in+every+other+country+in+Europe.+The+latter+situation+will+change+in+January+1993,+when+white+will+be+allowed+in+France+as+a+result+of+the+integration+of+the+European+Community |access-date=7 August 2018}}</ref> so for many years yellow headlights visually marked French-registered cars wherever they were seen,<ref name="CountryLife">{{cite journal |title=Rallying to the Call |journal=Country Life |date=May 1992 |page=98 |url= https://books.google.com/books?id=tD08AAAAMAAJ&q=Yellow+headlights,+for+many+years+the+sure+sign+of+a+French-registered+car,+are+to+be+phased+out,+following+a+decision+to+standardise+regulations+for+cars+sold+in+the+EC |access-date=7 August 2018}}</ref> though some French drivers are said to have switched to white headlamps despite the requirement for yellow ones.<ref>{{cite book |title=Official Journal of the European Communities: Information and notices, Volume 27 |year=1984 |publisher=Office for Official Publications of the European Communities |url= https://books.google.com/books?id=aGYNAQAAMAAJ&q=The+car+was+equipped+with+the+obligatory+yellow+headlights,+although+more+and+more+French+drivers+are+switching+to+clear+lights,+in+breach+of+the+regulations |access-date=7 August 2018}}</ref>

The requirement was criticised as a [[trade barrier]] in the automobile sector;<ref>{{cite book |last1=Maloney |first1=William A. |last2=McLaughlin |first2=Andrew |title=The European Automobile Industry: Multi Level Governance, Policy and Politics |year=2005 |publisher=Routledge |isbn=9781134829262 |page=183 |url= https://books.google.com/books?id=VKuIAgAAQBAJ&q=French+trade+yellow+headlamps&pg=PA183 |access-date=7 August 2018}}</ref> French politician [[Jean-Claude Martinez]] described it as a [[Protectionism|protectionist law]].<ref>{{cite journal |title=Europe |journal=International Trade Reporter |year=2008 |volume=25 |issue=9 |page=302 |url= https://books.google.com/books?id=U8FEAQAAIAAJ&q=French+lawmaker+Jean-+Claude+Martinez+cited+his+country%27s+long-held+protectionist+rule+that+automobile+headlamps+must+project+a+yellow+beam |access-date=6 August 2018}}</ref>

Formal research found, at best, a small improvement in visual acuity with yellow rather than white headlights,<ref name="LR156"/><ref name="SWOV1976"/> and French automaker [[Peugeot]] estimated that white headlamps produce 20 to 30 percent more light—though without explaining why this estimate was larger than the 15% to 18% value measured in formal research—and wanted drivers of their cars to get the benefits of extra illumination.<ref>{{cite news |title=Science and Technology |newspaper=The Economist |year=1992 |volume=322 |page=86 |url= https://books.google.com/books?id=6_LtAAAAMAAJ&q=French+car+maker,+thinks+that+white+ones+produce+20-30%25+more+light,+and+wants+its+drivers+to+get+the+benefits+that |access-date=7 August 2018}}</ref> More generally, country-specific vehicle technical regulations in Europe were regarded as a costly nuisance. In a survey published in 1988, automakers gave a range of responses when asked what it cost to supply a car with yellow headlamps for France. [[General Motors]] and [[Lotus Cars|Lotus]] said there was no additional cost, [[Rover Company|Rover]] said the additional cost was marginal, and [[Volkswagen]] said yellow headlamps added 28 [[Deutsche Mark]]s to the cost of vehicle production.<ref>{{cite book |title=Research on the "Cost of Non-Europe": The EC 92 automobile sector |volume=11 |year=1988 |publisher=Office for Official Publications of the European Communities |pages=12, 54, 310–333 |author=Ludvigsen Associates |url= http://aei.pitt.edu/47981/1/A9319.pdf |access-date=8 August 2018}}</ref> Addressing the French requirement for yellow lights (among other country-specific lighting requirements) was undertaken as part of an effort toward common vehicle technical standards throughout the [[European Communities|European Community]].<ref name="hearings-1993"/><ref name="CountryLife"/> A provision in [[Council of the European Union|EU Council]] [[Directive (European Union)|Directive]] 91/663, issued on 10 December 1991, specified white headlamps for all new vehicle type-approvals granted by the EC after 1 January 1993 and stipulated that from that date EC (later EU) member states would not be permitted to refuse entry of a vehicle meeting the lighting standards contained in the amended document<ref name="EC91663">{{cite book |title=Commission Directive of 10 December 1991 adapting to technical progress Council Directive 76/756/EEC relating to the installation of lighting and light-signalling devices on motor vehicles and their trailers |year=1991 |url= https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:31991L0663&from=en |access-date=8 August 2018}}</ref>—so France would no longer be able to refuse entry to a vehicle with white headlights. The directive was adopted unanimously by the council, and hence with France's vote.<ref name="Schoutheete">{{cite book |last=Schoutheete |first=Philippe de |title=The Case for Europe: Unity, Diversity, and Democracy in the European Union |year=2000 |publisher=Lynne Rienner Publishers |isbn=9781555879006 |page=47 |url= https://books.google.com/books?id=1XyHxCCcZ-YC&q=White+headlamps+compulsory+for+vehicles+first+registered+1993+at+request+of+French+car+manufacturers&pg=PA47 |access-date=19 July 2018}}</ref>

Though no longer required in France, selective yellow headlamps remain legal there; the current regulation stipulates that "every motor vehicle must be equipped, at the front, with two or four lights, creating in a forward direction selective yellow or white light permitting efficient illumination of the road at night for a distance, in clear conditions, of 100 metres".<ref>{{cite web |title=Section 1: Eclairage et signalisation des véhicules |url= https://www.legifrance.gouv.fr/affichCode.do;jsessionid=D751DF10CDEFA64A4B3DF1EB08E113FE.tpdjo06v_3?idSectionTA=LEGISCTA000006177087&cidTexte=LEGITEXT000006074228&dateTexte=20150101 |website=legifrance.gouv.fr |publisher=Code de la route. Legifrance |language=fr |access-date=7 August 2018}}</ref>