This week, Tanzanian authorities arrested 10 men after a politician asked citizens to report suspected homosexuals. These men will be subjected forced anal exams, a medical form of state-sanctioned rape incapable of proving a man’s homosexuality.

Here are the grim details of such examinations and some of the organizations opposing them.

The ten men were arrested during a police raid at a Pongwe Beach party on Saturday, Nov. 3. The men have since been held without charges.

“We now fear these men may be subjected to forced anal examination, the government’s method of choice for ‘proving’ same-sex sexual activity among men,” said Seif Magango, Amnesty International Deputy Director for East Africa. “This must not be allowed to happen — these men must be released immediately.”

Related: Tanzanian governor wants people to report suspected gay men so they can be arrested

Tanzanian laws punish homosexuals with prison sentences lasting anywhere from three years to a lifetime. The country is one of eight that uses anal examinations to “confirm” suspected homosexuality. The other seven are Cameroon, Egypt, Lebanon, Tunisia, Turkmenistan, Uganda and Zambia.

These anal exams aren’t really meant to prove past engagement in anal sex. Rather, they’re used to humiliate and intimidate people accused of sexual deviance.

If men refuse an anal examination, their refusal can be used in court as “obstruction of justice” or “proof” of their guilt.

During these “exams,” men are physically restrained, their pants removed while a doctor inserts a tube or finger into the anus. Doctors then search for any signs of anal “looseness,” tears, lesions, redness, inflammation, or traces of sperm.

The doctors can allow anyone to assist, observe or take photos, adding to the humiliation.

A group of 35 international forensic doctors with the Independent Forensic Experts Group (IFEG) have called the examinations “useless”, stating that numerous medical conditions can create loosened or inflamed anuses, none of which are related homosexuality or anal sex. The psychological damage caused by such exams can last for years.

In April 2017, Tunisia’s National Council of the Medical Order issued a statement calling the exams an unjustified violation of individual integrity and called for their end. Similarly, the United Nations Committee Against Torture has condemned the practice as “cruel, inhuman, and degrading.”