On Monday, President Donald Trump signed an executive order prohibiting inmates who are biological males from being housed at female federal prisons.

According to the Daily Caller, the order would impact at least 15% of the current population of federal prisons designated for female inmates, as the number of male prisoners who choose to identify as women has skyrocketed. The Federal Bureau of Prisons confirmed that out of 10,047 inmates in federal female prisons across the county, 1,538 are men.

The order also forbids the use of federal funds for transgender surgeries for prisoners, as well as hormone therapy and other treatments for those claiming to be of the opposite gender.

“The Attorney General and Secretary of Homeland Security shall ensure that males are not detained in women’s prisons or housed in women’s detention centers,” the order declares, also noting that “any medical procedure, treatment, or drug for the purpose of conforming an inmate’s appearance to that of the opposite sex.”

Several far-left groups have already announced or hinted at intentions to file lawsuits to block the order’s implementation, with the American Civil Liberties Union (ACLU) falsely describing the order as “a plan to erase transgender people’s existence under the law.” Another pro-LGBT group, Lambda Legal, has called the order unconstitutional.