Lesbian, gay, bisexual and transsexual (LGBT) individuals are disproportionately incarcerated, mistreated and sexually victimized in U.S. jails and prisons, researchers say.

Rainbow whistles are shown hanging at the San Francisco Gay Pride Parade in San Francisco, California June 30, 2013. REUTERS/Jed Jacobsohn

Just the proportion of women in prisons and jails identifying as lesbian and bisexual is eight times greater than the 3.4 percent of U.S. women overall who identify as lesbian or bisexual, they found.

“The high rate was so shocking, I had to check it three times to make sure we weren’t making any mistakes,” said lead study author Ilan Meyer, the Williams Distinguished Senior Scholar for Public Policy at the University of California, Los Angeles School of Law.

“We’ve received mixed reactions, and some people still don’t believe it,” he told Reuters Health. “However, there is no reason to suspect it or think there’s an error.”

Meyer and colleagues drew data from the 2011-2012 National Inmate Survey, which interviewed a representative sample of people in U.S. prisons and jails. Their analysis found that rates of incarceration for lesbian, gay and bisexual people were 1,882 per 100,000. That is more than three times the “already high” incarceration rate of 612 per 100,000 U.S. population, the authors write in the American Journal of Public Health.

“Importantly, the data distinguishes between sexual orientation, sexual identity and sexual behavior,” Meyer said. “Not everyone who has had a same-sex experience identifies as gay, and we were able to look at several measures.”

In total, sexual minorities - LGBT individuals or those who reported a same-sex sexual experience before arrival at the facility - represented 9.3 percent of all men in prison, 6.2 percent of men in jail, 42.1 percent of women in prison and 35.7 percent of women in jail.

Since the Prison Rape Elimination Act of 2003, the U.S. Department of Justice Bureau of Justice Statistics has collected data about the sexual victimization of inmates. Jails are short-term facilities that hold inmates for trial, sentencing or terms less than one year for misdemeanors, and prisons are long-term facilities that hold inmates and felons for terms longer than one year.

Meyers and his coauthors cite past Bureau analyses of their own survey data that found 12 percent of incarcerated sexual minorities say they’ve been sexually victimized by another inmate and 5 percent say they’ve been sexually victimized by staff, as compared with 1.2 percent and 2.1 percent, respectively, of heterosexual inmates.

Sexual minorities were also more likely to experience solitary confinement and to report psychological distress, the new study found.

The data showed as well that sexual minorities were more likely than heterosexual prisoners to report sexual victimization as a child and to be incarcerated for violent sexual and nonsexual crimes rather than crimes related to property, drugs or parole violations.

“This raises a lot of questions and a call-to-action for policy changes in both jails and prisons,” Meyer said. “In a similar way we’re discussing race and incarceration, the experience seems to be different across the whole criminal justice process for minorities.”

In both prisons and jails, lesbian or bisexual women were sentenced to longer periods of time than straight women. Gay or bisexual men were also more likely than straight men to have sentences longer than 10 years in prison.

“The burning question is: How did such a high proportion of LGB men and women end up incarcerated?” Meyer said. “Where is the root of this?”

Future research should investigate the pathways that lead LGBT men and women to incarceration, including the effects of prejudice, stigma and social disadvantage, he said.

The study authors speculate that prejudice toward sexual minorities may lead to discriminatory treatment, from initial contact with law enforcement, such as overpolicing of sexual offenses. Also, family rejection, illegal drug use and community-level marginalization may increase the risk of incarceration.

For women in particular, failing to conform to societal norms of femininity, such as being labeled as masculine, aggressive or threatening, may lead to differences in treatment in the criminal justice system the study team writes.

“We need to understand whether there are biases ingrained in our court system that lead to sexual minorities being handled in a different way,” Meyer said. “With race, this is nothing new, and now we’re seeing it’s also true for the sexual minority population.”