In a trio of cases heard in October, the Supreme Court weighed whether discrimination against LGBT people should be legal. Over the course of those and related cases, a handful of scholars who oppose legal protections for LGBT Americans claimed in a legal brief that “research about discrimination and its effects” on LGBT people is “deficient and the claims based on it unsupported.” This claim rings false to many researchers who study this issue, as well it should, because the evidence of a link between anti-LGBT discrimination and health harms is both robust and well-supported.

That’s not just idle supposition. Our research team at the What We Know Project, an initiative of Cornell University’s Center for the Study of Inequality, sought to better understand what is known about the link between discrimination and LGBT well-being. To that end, we spent two years conducting the largest known review of the peer-reviewed scholarship on the relationship between anti-LGBT discrimination and health harms. What we found is a remarkably consistent conclusion that discrimination harms LGBT people in far-reaching — and sometimes life-threatening — ways.

The stakes of these findings are high: If the presence of stigma, prejudice and discrimination harms LGBT people — and the research shows that it does — learning how to reduce those harms may be a matter of life and death. Questions about the impact of discrimination have a bearing not only on court cases and pending legislation in Congress and many states but also on the policies and practices of hospitals, businesses and other organizations seeking to balance religious liberty with the concrete harms that discrimination can cause LGBT people.

Our review screened more than 11,000 peer-reviewed articles in a systematic, comprehensive literature search that yielded more than 1,300 articles investigating the link between anti-LGBT discrimination and health and well-being. We read the full text of those articles and identified all the studies that addressed whether discrimination affects the health of LGBT people.

We further narrowed the studies by excluding those that did not use a U.S.-based sample, lacked a quantitative methodology, or did not specifically measure victimization based on subjects’ sexual orientation or gender identity.

Our final study list comprised 300 articles. Of these, less than 5 percent (14 studies) failed to identify a link between anti-LGBT discrimination and health harms. Nearly 82 percent (245 studies) found unambiguous evidence that discrimination on the basis of sexual orientation or gender identity is associated with harms to the health of LGBT people, while almost 14 percent (41 studies) reported mixed effects. Overall, more than 95 percent of the 300 studies showed a connection between discrimination and health harms for LGBT people.

The harms those studies describe are substantial. Prejudice, stigma and discrimination against LGBT people raise the risks of depression, anxiety, suicidality, PTSD and other forms of psychological distress. Discrimination is linked to health harms even for those who are not directly exposed to it because the presence of discrimination, stigma, prejudice and fear of victimization (the FBI reports hate crimes against LGBT people are on the rise) create a hostile social climate that contributes to what researchers call “minority stress.” Even for the most resilient, exposure to discrimination — experiencing it or fearing it — is hurtful.

Minority stress also has measurable physiological effects. For instance, a study measuring the stress hormone cortisol among transgender people found that encountering barriers in access to public restrooms predicted higher levels of stress. A large body of medical literature shows higher levels of stress hormones are associated with physical health consequences such as cardiovascular disease and high blood pressure.

All these findings help explain disparities such as the alarmingly high levels of suicidal thoughts and attempts among LGBT youth, which researchers have found to be between two and seven times the rate it is for their peers. The research also puts to rest the old notion that there is something inherently destabilizing about being LGBT, such as the idea that these identities themselves are mental illnesses. Instead, stigma and prejudice — negative social messages, discriminatory policies and exclusionary institutional practices — are responsible for the disproportionate health harms LGBT people experience.

Some of the most compelling research we encountered comes from longitudinal studies comparing states that protect LGBT people from discrimination with those that allow it. A 2018 study by scholars at Harvard and other universities looked at psychological measures before and after some states passed laws essentially creating a license to discriminate on religious grounds. They found “the proportion of sexual minority adults reporting mental distress increased by 10.1 percentage points” in the two years between 2014 and 2016 in states that passed laws permitting denial of services to same-sex couples. Compared with control states, this was a 46 percent relative increase in sexual minorities experiencing mental distress. That’s powerful evidence that policies or practices that deny a gay couple a wedding cake are not mere expressions of religious freedom — they inflict genuine psychological harm. Similarly, a study conducted at Yale examined mental health outcomes in the three years between 2002 and 2005 in states that passed constitutional amendments banning same-sex marriage. The authors concluded that lesbian, gay and bisexual residents of states with same-sex marriage bans were significantly more likely to suffer from psychological distress than those in LGBT-friendly states.

The extensive evidence of the harms of discrimination is cause for grave concern. But the data also give us promising insight into what can be done about it. The authors of the Yale study concluded that, while “living in states with discriminatory policies may have pernicious consequences for the mental health of LGB populations,” the “findings lend scientific support to recent efforts to overturn these policies.” Other evidence corroborates this contention, showing that LGBT health outcomes improve when states implement policies of equal treatment. For instance, a 2017 study found suicide attempts by LGBT youth dropped by 7 percent in states that legalized same-sex marriage. Authors of another study concluded “policies that confer protections to same-sex couples may be effective in reducing health care use and costs among sexual minority men.” Indeed, our research pointed to several consistent factors known to protect LGBT individuals against the harms of stigma and discrimination. These include supportive families and peer communities; access to LGBT-affirmative health care and social services; and anti-discrimination policies and practices in organizations, businesses and at various levels of government.

Whatever you may think about whether Americans should have the right to discriminate, it’s clear that exercising that right — whether by denying someone a job, refusing them a wedding cake or even making it harder for them to walk home safely — damages the health and well-being of LGBT people. As these matters are litigated in courts and in the court of public opinion, let us remember the human toll that discrimination inflicts. As a society, we know how to dramatically reduce this suffering if we only have the will to do it.