Public health accomplishes its work to improve the public's health through the 3 core functions of assessment, policy development and assurance, and the corresponding 10 essential services. This framework defines the lens through which public health practitioners utilize their legal authorities and work to establish new law and policy. Merriam-Webster defines the law as “a binding custom or practice of a community: a rule of conduct or action prescribed or formally recognized as binding or enforced by a controlling authority.”1 The law establishes the authorities necessary to define policy from its development through its enforcement. Public policy also has a profound impact on how public health does its work and impacts the health of both individuals and populations.
Legal epidemiology is an emerging field of study that looks at how the law impacts the etiology of disease, its ultimate distribution, prevention and treatment, and both individual and population health. Public health practitioners can use legal epidemiology to better understand how the law, translated into policy and regulation, acts as a social determinant of health. Through an improved understanding of this relationship, practitioners can maximize their health improvement efforts for both chronic disease and noncommunicable disease prevention.
The United States has a patchwork of laws, policies, and regulations. This mosaic creates an opportunity for a comparison analysis of the impact of law and policy between jurisdictions with similar demographics and other social determinants but different laws, policies, and regulations. When one looks at the differences between states, cities, counties, and even zip codes where different policy choices have been made on the basis of divergent laws, we can see different health outcomes. Ranking tools such as the Robert Wood Johnson Foundation County Health Rankings (https://www.countyhealthrankings.org/), United Health Foundation America's Health Rankings (https://www.americashealthrankings.org/), and US News & World Report Healthiest Communities Rankings (https://www.usnews.com/news/healthiest-communities) are examples of annual reviews that compare legal jurisdictions on the basis of health and social determinants. What we see through these assessments is that there are significant differences even between communities blocks apart.
Access to Care
Access to care is profoundly impacted by access to affordable health insurance (it has been shown that people die prematurely simply because they lack health insurance).2 To help increase health insurance coverage nationwide, the Patient Protection and Affordable Care Act was signed into law on March 23, 2010. Originally, the law required all states to expand their Medicaid insurance programs to cover all uninsured and eligible people with incomes up to 133% of the federal poverty level. In 2012, the law was challenged by several states, and in a landmark ruling, the US Supreme Court ruled in the case National Federation of Independent Business v. Sebelius, 567 US 519, that the Affordable Care Act was constitutional and upheld most of its provisions. The court did, however, strike down the mandatory requirement for Medicaid expansion, making it voluntary for states. In the years since this ruling, the nation's patchwork of insurance coverage has continued, but a clear pattern of almost universal coverage has developed in some states, compared with a persistent or a growing number of the uninsured in others. We now observe significant differences in health outcomes, including mortality, between those states that expanded coverage compared with those that have not expanded. By comparing health outcomes at the state level using legal epidemiologic tools, one can more clearly understand the impact of health insurance coverage on populations.
Using the law to impact the distribution of businesses that have a negative impact on health has been shown to be a powerful influencer of health. Zoning regulations are one such type of law. Zoning is the process of dividing land into zones that describe how the land is to be used. Through this process, types of structures, housing, businesses, and industrial uses are prohibited or permitted. In many communities, excess liquor stores exist, which is believed to be a contributing factor to increased alcohol consumption and violence. Researchers have studied how governments that have used zoning for more effective planning that resulted in reduced liquor stores have seen community reductions in excess drinking and violence.3
Another example is the use of planning to improve the built environment, which is a major influencer of health. Through ensuring that communities are walkable, bikeable, and green, communities can ensure better opportunities for preventive health, health maintenance, and overall wellness. Recent work that measures the temperature of urban communities has shown disparities in heat exposure between underserved communities and more affluent communities. This is due to the urban heat island effect. Recent studies show that black communities tend to have fewer trees and more heat-trapping pavement, and “the rate of heat-related deaths in African Americans is 150–200% greater than that for non-Hispanic Whites.”4 Researchers at the University of California, Berkeley, reported that people of color were as much as 52% more likely to live in parts of the city that were the warmest. Studies that have mapped the heat patterns over several urban areas have found that lower-income communities are as much as 10° hotter than wealthier communities.4,5 Policies that use planning processes, zoning, planting of trees, reduced use of heat-trapping materials, and green building codes can help reduce health inequities. Research studies in this issue of the journal show the impact of housing and environmental law as examples of the impact of legal epidemiology.
Health Promotion, Disease Prevention, and Social Supports
Health promotion is a proven method for improving health. Opportunities to evaluate legal differences in law and policy between communities to better understand the legal framework for health promotion education abound: injury prevention, nutritional labeling, substance misuse, and restaurant inspection scoring are examples of areas that will benefit from study. In addition, comparing the disease prevention impact of taxes on soda, tobacco, and alcoholic beverages can result in opportunities to improve the effectiveness of these economic measures to improve health.
A range of policies being debated at the national level around social programs such as Medicare and Medicaid, Social Security, and immigration are underscoring significant potential changes in those policies and programs. The impacts of these changes are highly controversial and generally believed to not be in the best interest of the population. For example, a recently proposed change in immigration eligibility policy is expected to have negative impacts on health care access.6 Another policy change designed to reduce access to funding support for food has the potential to increase health costs. In 1 study, the Supplemental Nutrition Assistance Program has been shown to actually reduce health care costs in eligible populations.7 A scientific evaluation of the health impact of these changes through a legal epidemiologic lens can help inform any modification or reversal of these legal changes.
The Future of Legal Epidemiology
Tobacco control policies are abundant in the United States, but as a study in this issue of the journal shows, local tobacco control efforts can be significantly impacted by state preemption of local laws. The lessons learned by examination of the state/local legal interaction can inform further local efforts to protect their populations from health threats even when major differences in policy exist between elected leaders at the state and local levels. Lessons learned may also be helpful when exploring federal/state differences in law.
Nine of the top 10 leading causes of death are noncommunicable in nature (cardiovascular disease, cancer, injury, chronic obstructive lung disease, stroke and cerebrovascular diseases, Alzheimer's disease, diabetes, kidney disease, and suicide). Adding in arthritis and back pain, the 2 leading causes of disability, creates a focused list of diseases in which a structured approach using legal epidemiology as a component of a health improvement effort could have enormous impact on the health of Americans. When one considers that these diseases carry some of the largest health disparities, an encouraging opportunity to narrow health inequities using legal studies also exists.
Emerging areas of study with major differences in law between federal, state, and local government include marijuana, opioids, firearms, reproductive health, climate change solutions, and water fluoridation. These are areas of policy and practice that are highly controversial and political. They are often driven by major differences in ideology and because of these firmly held beliefs, variances in policy approaches and the law will not be resolved anytime soon. Yet, the opportunity to understand the differences in what works and how differences in law and policy—even driven by different ideologies—can improve health is where legal epidemiology will have the biggest impact.
Legal epidemiology is a tool that has the potential for broad utilization across the full spectrum of chronic and noncommunicable disease. Public health practitioners can use the science and observations of legal epidemiologists to improve their policy making and thereby improve the overall health of their communities.
1. Merriam-Webster Dictionary. https://www.merriam-webster.com/
. Published 2019. Accessed October 14, 2019.
2. Wilper A, Woolhandler S, Lasser K, McCormick D, Bor D, Himmelstein D. Health insurance and mortality in US adults. Am J Public Health. 2009;99(12):2289–2295.
3. Ashe M, Jernigan D, Kline R, Galaz R. Land use planning and the control of alcohol, tobacco, firearms, and fast food restaurants. Am J Public Health. 2003;93(9):1404–1408.
4. Benjamin G. Killer climate: more Americans are dying from extreme heat. The Hill. September 9, 2019.
5. Jesdale B, Morello-Frosch R, Cushing L. The racial/ethnic distribution of heat risk–related land cover in relation to residential segregation. Environ Health Perspect. 2013;121(7):811–817.
6. Perreira K, Yoshikawa H, Oberlander J. A new threat to immigrants' health—the public-charge rule. N Engl J Med. 2018;379(10):901–903.
7. Bleich SN, Rimm EB, Brownell KD. U.S. nutrition assistance, 2018—modifying SNAP to promote population health. N Engl J Med. 2017;376(13):1205–1207.