A Sikh combat solider sued the United States Defence Department on 29 February, citing claims of "religious discrimination". Simratpal Singh said that his beard and turban had prompted the US Army to make him undergo three days of performance tests that other soldiers had not been subject to.

The complaint was filed in the Federal District Court in Washington, the New York Times reported. Singh claimed that the Army put him through helmet and gas mask testing, which others did not have to do. The Army has had a ban on long hair and beards, which they say are a battlefield liability as helmets and gas masks are required to fit properly.

After receiving his temporary 'accommodation' – a licence to grow a beard and long hair given by the army – in December 2015, Singh said: "I have so much pride in my Sikh identity and service to my nation. To feel spiritually whole, while continuing my military career, has always been the dream."

Singh is now being represented by lawyers from the Sikh Coalition, the Becket Fund for Religious Liberty and law firm McDermott Will and Emery. A spokesperson for the Sikh Coalition said that Singh was granted temporary accommodation until 31 March 2016 to serve in the Army while maintaining his Sikh articles of faith, including a turban and beard. On 26 February 2016 he was allegedly ordered to report for additional testing as a precondition for remaining in the Army.

Harsimran Kaur, the Sikh Coalition's legal director, said: "Captain Singh is being subject to discriminatory testing that isn't required of any other soldiers, even those with medical or religious accommodations. The Army cannot delay in providing him his statutory and constitutionally mandated right to an accommodation to serve as an observant Sikh in the Army."

Singh's lawyers at McDermott Will and Emery also confirmed that soldiers that had been allowed to maintain beards for medical reasons, as well as previously-accommodated Sikhs, had not been asked to report for additional testing. The Army has permitted about 100,000 troops to maintain beards for medical reasons, and in recent years it allowed Special Forces troops in Afghanistan to grow beards.

The Sikh Coalition and McDermott Will & Emery have also represented the only three other Sikh Americans who have been granted the right to serve full time without cutting their hair or their beards.

Amandeep Sidhu, partner at McDermott Will and Emery, said that they had worked to avoid a litigation under the belief that the Army would do the right thing. Singh enrolled in West Point in 2006 and was met with failed attempts to obtain an accommodation. He was then forced to have his hair cut and shave his beard in order to serve in the Army.

Sidhu said: "The US Constitution and the Religious Freedom Restoration Act make it clear that Captain Singh has the right to practice his faith in the military and we are confident that the court will agree."