In filings late Tuesday in the US Court of Appeals in San Francisco, the groups said Trump’s abrupt reversal in July 2017 of former President Barack Obama’s policy of inclusion contradicted past studies on the subject and mimicked earlier periods of discrimination against other groups in the military.

A friend-of-the-court brief by the National Association for the Advancement of Colored People’s Legal Defense Fund compared Trump’s ban on transgender military service to arguments made almost 70 years ago against service by African-Americans and against racially integrated military units.

The justifications the Trump administration cited to re-impose the ban on transgender soldiers are “almost identical to the justifications the military used to discriminate against Black soldiers more than half a century ago,” the civil rights group said.

Trump announced in July 2017, on Twitter, that transgender Americans would be barred from serving in the military “in any capacity.” That triggered at least four court injunctions, preventing the policy from taking effect while litigation proceeded. A March version of the ban, which Defense Secretary James Mattis said was crafted by military experts, would allow transgender people to serve openly in their “biological sex.” A federal judge put both versions of the ban on hold, triggering the appeal.