{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T18:13:27Z","timestamp":1788200007364,"version":"build-2803163510"},"reference-count":49,"publisher":"BMJ","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["Inj Prev"],"accepted":{"date-parts":[[2026,8,20]]},"abstract":"<jats:p>Since the turn of the century, there has been a drumbeat among those opposed to regulations, including safety regulations, to talk about a \u201claw\u201d of unintended consequences. The law claims that regulations commonly have large negative unanticipated effects. But in the injury prevention field, regulations actually seem to have few such large negative unintended consequences and many positive unintended consequences. This essay describes a half dozen instances of beneficial unanticipated consequences that appear to have been caused by regulations, such as that motorcycle helmet laws not only reduced head injuries to cyclists but also seem to have reduced the theft of motorcycles; a higher minimum legal drinking age not only reduced motor vehicle deaths for those aged 18\u201320 but also likely reduced suicides among that age group; a successful Air Force suicide prevention initiative not only reduced suicide but also seems to have reduced interpersonal violence and seat belt laws not only increased seat belt wearing but also appear to have increased positive attitudes about both seat belt use and mandatory seat belt laws. The \u201claw\u201d of unintended consequences seems similar to \u201cMurphy\u2019s Law\u201d (ie, anything that can go wrong will go wrong) in that while both laws correctly warn that policymaker overconfidence can lead to unwanted and detrimental outcomes, both are less similar to empirical laws than they are to humorous adages that are usually incorrect. While there are many actual empirical economic \u201claws\u201d, the \u201claw\u201d of unintended consequences does not appear to be one of them.<\/jats:p>","DOI":"10.1136\/ip-2026-046334","type":"journal-article","created":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T17:20:20Z","timestamp":1788196820000},"page":"ip-2026-046334","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["There is no law of unintended consequences: positive unintended consequences in injury prevention"],"prefix":"10.1136","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8125-1690","authenticated-orcid":false,"given":"David","family":"Hemenway","sequence":"first","affiliation":[{"name":"Harvard School of Public Health, Boston, Massachusetts, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,8,31]]},"reference":[{"key":"2026083110201061000_ip-2026-046334v1.1","doi-asserted-by":"crossref","unstructured":"Hirschman AO . The rhetoric of reaction: Perversity, futility, jeopardy. Cambridge, MA: Harvard University Press, 1991.","DOI":"10.2307\/j.ctvjnrs9q"},{"key":"2026083110201061000_ip-2026-046334v1.2","doi-asserted-by":"publisher","DOI":"10.2307\/1192211"},{"key":"2026083110201061000_ip-2026-046334v1.3","first-page":"433","article-title":"From invisible hands to perversity: \u201cunintended consequences\u201d as neoliberal rhetoric","volume":"5","author":"Faust","year":"2025","journal-title":"J Law Polit Econ"},{"key":"2026083110201061000_ip-2026-046334v1.4","unstructured":"Davis M . In: Unintended consequences. Melbourne, FL: Publifye AS, 2025."},{"key":"2026083110201061000_ip-2026-046334v1.5","unstructured":"Norton R . Unintended consequences. In: Henderson DR , ed. The concise encyclopedia of economics. Library of Economics and Liberty, 2007. Available: https:\/\/www.econlib.org\/library\/Enc\/UnintendedConsequences.html"},{"key":"2026083110201061000_ip-2026-046334v1.6","doi-asserted-by":"publisher","DOI":"10.1086\/260352"},{"key":"2026083110201061000_ip-2026-046334v1.7","doi-asserted-by":"crossref","first-page":"587","DOI":"10.1080\/00213624.1977.11503463","article-title":"A critical analysis of Peltzman\u2019s \u201cThe Effects of Automobile Safety Regulation\u201d","volume":"11","author":"Robertson","year":"1977","journal-title":"J Econ Issues"},{"key":"2026083110201061000_ip-2026-046334v1.8","first-page":"1","article-title":"Risky business: when safety regulations cause harm","volume":"6","author":"Abdukakirov","year":"2014","journal-title":"William Mary Policy Rev"},{"key":"2026083110201061000_ip-2026-046334v1.9","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.332.7543.722"},{"key":"2026083110201061000_ip-2026-046334v1.10","doi-asserted-by":"publisher","DOI":"10.1086\/467100"},{"key":"2026083110201061000_ip-2026-046334v1.11","unstructured":"Perry MJ . Ten examples of the law of unintended consequences. Five Examples of the Law of Unintended Consequences; 2013. Available: https:\/\/www.aei.org\/carpe-diem\/ten-examples-of-the-law-of-unintended-consequences"},{"key":"2026083110201061000_ip-2026-046334v1.12","doi-asserted-by":"crossref","first-page":"239","DOI":"10.1016\/j.aap.2018.08.001","article-title":"Recommend or mandate? A systematic review and meta-analysis of the effects of mandatory bicycle helmet legislation","volume":"120","author":"Hoye","year":"2018","journal-title":"Accident Anal Prev"},{"key":"2026083110201061000_ip-2026-046334v1.13","doi-asserted-by":"publisher","DOI":"10.1162\/003465303772815754"},{"key":"2026083110201061000_ip-2026-046334v1.14","doi-asserted-by":"publisher","DOI":"10.1111\/j.1540-6237.2007.00510.x"},{"key":"2026083110201061000_ip-2026-046334v1.15","doi-asserted-by":"crossref","first-page":"513","DOI":"10.1002\/jae.3026","article-title":"Mandatory seatbelt laws and traffic fatalities: A reassessment","volume":"39","author":"Anderson","year":"2024","journal-title":"J Appl Econometrics"},{"key":"2026083110201061000_ip-2026-046334v1.16","doi-asserted-by":"publisher","DOI":"10.1001\/archpedi.156.9.929"},{"key":"2026083110201061000_ip-2026-046334v1.17","doi-asserted-by":"publisher","DOI":"10.1080\/17457300.2016.1224901"},{"key":"2026083110201061000_ip-2026-046334v1.18","doi-asserted-by":"crossref","unstructured":"Lepard JR , Spagiari R , Corley J , et al . n.d. Differences in outcomes of mandatory motorcycle helmet legislation by country income level: A systematic review and meta-analysis. PLoS Med 18:e1003795. doi:10.1371\/journal.pmed.1003795","DOI":"10.1371\/journal.pmed.1003795"},{"key":"2026083110201061000_ip-2026-046334v1.19","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1111\/j.1468-2311.1989.tb00631.x","article-title":"Motorcycle theft, helmet legislation and displacement","volume":"28","author":"Mayhew","year":"1989","journal-title":"Howard J Crim Just"},{"key":"2026083110201061000_ip-2026-046334v1.20","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1016\/S0749-3797(01)00381-6","article-title":"Reviews of evidence regarding interventions to reduce alcohol-impaired driving","volume":"21","author":"Shults","year":"2001","journal-title":"Am J Prev Med"},{"key":"2026083110201061000_ip-2026-046334v1.21","doi-asserted-by":"crossref","first-page":"108","DOI":"10.15288\/jsads.2014.s17.108","article-title":"Case closed: research evidence on the positive public health impact of the age 21 minimum legal drinking age in the United States","volume":"17","author":"DeJong","year":"2014","journal-title":"J Stud Alcohol Drugs Suppl"},{"key":"2026083110201061000_ip-2026-046334v1.22","doi-asserted-by":"publisher","DOI":"10.2105\/AJPH.89.9.1365"},{"key":"2026083110201061000_ip-2026-046334v1.23","doi-asserted-by":"crossref","first-page":"103057","DOI":"10.1016\/j.eclinm.2024.103057","article-title":"The impact of the U.S federal minimum legal drinking age law on alcohol involved firearm suicide: a regression discontinuity approach","volume":"80","author":"Jain","year":"2025","journal-title":"eClinicalMedicine"},{"key":"2026083110201061000_ip-2026-046334v1.24","unstructured":"Centers for Disease Control . Suicide Prevention Among Active Duty Air Force Personnel\u2014United States, 1990\u20131999. 1999."},{"key":"2026083110201061000_ip-2026-046334v1.25","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.327.7428.1376"},{"key":"2026083110201061000_ip-2026-046334v1.26","unstructured":"Institute of Medicine (US) Committee on Pathophysiology and Prevention of Adolescent and Adult Suicide . In: Pellmar TC , ed. Reducing Suicide: A National Imperative. Washington (DC): National Academies Press (US), 2002."},{"key":"2026083110201061000_ip-2026-046334v1.27","doi-asserted-by":"crossref","first-page":"1243","DOI":"10.2105\/AJPH.76.10.1243","article-title":"The impact of \u201cBottle Bill\u201d legislation on the incidence of lacerations in childhood","volume":"76","author":"Baker","year":"1986","journal-title":"Am J Public Health"},{"key":"2026083110201061000_ip-2026-046334v1.28","doi-asserted-by":"publisher","DOI":"10.1016\/S0145-2134(99)00021-6"},{"key":"2026083110201061000_ip-2026-046334v1.29","doi-asserted-by":"publisher","DOI":"10.1136\/archdischild-2015-310119"},{"key":"2026083110201061000_ip-2026-046334v1.30","unstructured":"Seo P . Revisionist history: seat belts and resistance to public health measures. The Rheumatologist. Personal liberty; 2021."},{"key":"2026083110201061000_ip-2026-046334v1.31","unstructured":"NY Times . Poll Finds Increase in Public\u2019s Concern Over Cars. 1984.22."},{"key":"2026083110201061000_ip-2026-046334v1.32","unstructured":"Ipsos . USA Today\/Ipsos Poll: Common Good vs. Personal Liberty (Aug. 17\u201318, 2021). 2021. Available: https:\/\/www.ipsos.com\/en-us\/news-polls\/usa-today-common-good-2021"},{"key":"2026083110201061000_ip-2026-046334v1.33","doi-asserted-by":"publisher","DOI":"10.1016\/S0749-3797(02)00513-5"},{"key":"2026083110201061000_ip-2026-046334v1.34","unstructured":"Hodges H . Falling Prices: Cost of Complying with Environmental Regulations Almost Always Less Than Advertised. Economic Policy Institute Briefing Paper; 1997."},{"key":"2026083110201061000_ip-2026-046334v1.35","doi-asserted-by":"publisher","DOI":"10.1257\/jep.9.4.97"},{"key":"2026083110201061000_ip-2026-046334v1.36","first-page":"450","volume-title":"Handbook of innovation impact chapter","volume":"15","author":"Blind","year":"2016"},{"key":"2026083110201061000_ip-2026-046334v1.37","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1080\/15389588.2024.2317410","article-title":"Summary of influences that led to introduction of frontal airbags on US passenger vehicles","volume":"25","author":"Digges","year":"2024","journal-title":"Traffic Inj Prev"},{"key":"2026083110201061000_ip-2026-046334v1.38","unstructured":"GAO . Vehicle Safety: Technologies, Challenges, and Research and Development Expenditures for Advanced Air Bags. GAO-01-596; 2001."},{"key":"2026083110201061000_ip-2026-046334v1.39","doi-asserted-by":"publisher","DOI":"10.1136\/ip-2022-044635"},{"key":"2026083110201061000_ip-2026-046334v1.40","unstructured":"Lee J , Hounshell DA , Veloso FM . Innovation and technology policy: lesson from emission control and safety technologies in the US automobile industry. Working Paper 2007-21 prepared for the 2007 Sloan Industry Conference, Industry Studies Association (ISA) at Pitt. Available: http:\/\/isapapers.pitt.edu\/139"},{"key":"2026083110201061000_ip-2026-046334v1.41","unstructured":"Van Ratingen MR . Consumer ratings and their role in improving vehicle safety. In: Bjornberg KE , Hansson SO , Belin MA , et al , eds. The Vision Zero Handbook. Springer, 2020: 756\u201388."},{"key":"2026083110201061000_ip-2026-046334v1.42","doi-asserted-by":"crossref","first-page":"283","DOI":"10.1007\/s11186-015-9247-6","article-title":"Unintended but not unanticipated consequences","volume":"44","author":"de Zwart","year":"2015","journal-title":"Theor Soc"},{"key":"2026083110201061000_ip-2026-046334v1.43","doi-asserted-by":"crossref","unstructured":"Hemenway D . While We Were Sleeping: Success Stories in Injury and Violence Prevention. Berkeley, CA: University of California Press, 2009.","DOI":"10.1525\/9780520943407"},{"key":"2026083110201061000_ip-2026-046334v1.44","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pmed.1000210","article-title":"Relationship between vehicle emissions laws and Incidence of suicide by motor vehicle exhaust gas in Australia, 2001\u201306: An ecological analysis","volume":"7","author":"Studdert","year":"2010","journal-title":"PLoS Med"},{"key":"2026083110201061000_ip-2026-046334v1.45","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0044565","article-title":"Declines in the lethality of suicide attempts explain the decline in suicide deaths in Australia","volume":"7","author":"Spittal","year":"2012","journal-title":"PLoS One"},{"key":"2026083110201061000_ip-2026-046334v1.46","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1007\/s42448-018-0006-y","article-title":"Is the U.S. national decline in child physical abuse attributable to the decline in intimate partner violence and births to adolescent mothers?","volume":"1","author":"Runyan","year":"2018","journal-title":"Int Journal on Child Malt"},{"key":"2026083110201061000_ip-2026-046334v1.47","doi-asserted-by":"publisher","DOI":"10.2307\/2084615"},{"key":"2026083110201061000_ip-2026-046334v1.48","unstructured":"Slutkin G . The end of violence: Eliminating the world\u2019s most dangerous epidemic. New York: Little, Brown, 2026."},{"key":"2026083110201061000_ip-2026-046334v1.49","doi-asserted-by":"publisher","DOI":"10.1136\/ip.6.2.82"}],"container-title":["Injury Prevention"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/ip-2026-046334","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T17:20:24Z","timestamp":1788196824000},"score":1,"resource":{"primary":{"URL":"https:\/\/injuryprevention.bmj.com\/lookup\/doi\/10.1136\/ip-2026-046334"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,31]]},"references-count":49,"alternative-id":["10.1136\/ip-2026-046334"],"URL":"https:\/\/doi.org\/10.1136\/ip-2026-046334","relation":{},"ISSN":["1353-8047","1475-5785"],"issn-type":[{"value":"1353-8047","type":"print"},{"value":"1475-5785","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,31]]}}}