In pictures: Bizarre army lottery in Thailand where transgender women must prove they're not faking it

Every April, all 21-year-old Thai men face a life-changing choice: they can volunteer to serve in the army for six months, or opt to take their chances in a lottery. If they draw a black card they can skip military service, but if they draw a red one they must serve for two years.

Crowds of their friends and relatives watch in excitement as the young men pull a ticket out of a plastic bucket, determining whether or not they will have to serve in the military. Nobody wants a red card, which means serving for two years, with the chance of a posting in the dangerous south, where Muslim Malay separatists are fighting an insurgency.

Some wealthy and well-connected Thais have been known to pay bribes to keep their sons from military service, but others see the army and its basic salary as a way out of poverty and a means to discipline unruly sons.

Exemptions are made for those who are physically or mentally incapable. Transgender women are also exempted from having to serve in the army – but only if they can prove that they are not faking it. They must submit to a physical examination to check whether they have breasts or have undergone gender reassignment surgery.

Those with physical alterations or who show what the rules refer to as "gender identity disorder" are exempt from conscription, but those who have not undergone such changes must return for up to two more years, unless an army hospital certifies they have the "disorder". Trans women say the reference to a disorder stigmatises them. However, the army has softened its description from the previous "permanent mental disorder".

Thailand is widely seen as a paradise for gay and trans people. However, they cannot change the gender designation on their identity papers, despite a 2015 law against gender-based discrimination. "I was born male, so I must be here, as duty calls," said Kanphitcha Sungsuk, 21, as she waited for military officers to call her name and decide whether she would be drafted.

Jetsada Taesombat, executive director of the Thai Transgender Alliance for Human Rights, said the process is traumatic for many trans women: "Some are so stressed out they want to commit suicide to avoid conscription."

Some transgender women told Reuters they had been told to leave women's toilets so as to not "frighten" women. "Society looks on and thinks we are accepted, but it's actually not so," said Khwan Suphalak, 23. "We're always treated differently," she said, adding that hotels had barred her entry over her gender.