A federal judge on Tuesday landed a huge blow to U.S. President Donald Trump’s attempt to ban transgender people from serving in the military, stating that the move violated the Fifth Amendment.

In his first few days in office, Mr Trump had signed an executive order that allowed the dismissal of thousands of transgender service members as part of his efforts to stamp out gender “radical gender ideology” at federal level.

Several service members immediately sued, saying the policy, which may result in the dismissal of about 4,200 service members, amounted to illegal discrimination that violated their constitutional right to equal protection under the law.

Ruling on the matter on Tuesday, U.S. District Judge Ana Reyes rebuked Mr Trump for taking the “derogatory” decision and subsequently issued an injunction that allows trans troops to keep serving in the military. 

“The ban at bottom invokes derogatory language to target a vulnerable group in violation of the Fifth Amendment,” Ms Reyes wrote in her ruling.

Despite the government arguing that courts must defer to military judgment on military matters, Ms Reyes disagreed, saying the Trump administration had provided no legal justification for the ban and that “the law does not demand that the court rubber-stamp illogical judgments based on conjecture.”