The Pseudoscientific Disaster of Forced Anal Examinations

Many governments criminalize homosexuality and consensual same-sex sexual behavior. At the time of this writing, it is illegal in over 70 countries according to the International Lesbian, Gay, Bisexual, Trans and Intersex Association (ILGA). This is typically due to religious extremism and scientific ignorance. Many religious scriptures and societies are notoriously anti-gay and some of these societies invent invalid and pseudoscientific ideas about the nature, origin and content of homosexuality, as well as supposed “spiritual harms” and fake “cures”.

Governments who criminalize homosexuality would need to have a system for detecting gay men to give the appearance of legitimacy. Besides the usual techniques (such as surveillance, interrogation, and urging people to report their family, friends and relatives to the police) some of them have invented pseudoscientific methods for “detecting homosexuality” through anal examinations of the gross morphology of the anus or anal tone. It is essentially based on the same myth as virginity tests, which is the notion that penetration makes you have a loose vagina or anus. This is not true because tightness is largely under the control of the autonomous nervous system and depend on how relaxed and sexually aroused you are.

Due to the nature of these examinations and the risk to the person being subjected to it, it is typically done by force and without informed consent. Needless to say, forced anal examinations are based on pseudoscience and violates many ethical, legal and moral principles. This post surveys the arguments and evidence discussed in the paper called Statement on Anal Examinations in Cases of Alleged Homosexuality by the Independent Forensic Expert Group. More information about forced anal examinations and the eight countries where it happens can be found in this news item from International Rehabilitation Council for Torture Victims or this Human Rights Watch primer and this Human Rights Watch report. Cached version of the paper and the report can be found here and here.

Eight scientific reasons for why forced anal examinations do not work

So what are the scientific reasons for why forced anal examinations do not tell you anything reliable about anal tone or consensual, same-sex anal sex? Why should it be considered pseudoscience? Here are eight distinct reasons:

(1) There is no standardized and quantitative method for doing anal examinations of anal tone or appearance.

(2) There is no evidence that this method is valid, i.e. that certain level of anal tone or appearance is associated with receptive, same-sex anal sex.

(3) There is a certain degree of normal variability in anal features between individuals and examinations, which makes it hard to make claims about clinical relevant deviations.

(4) There is no evidence of interrater reliability i.e. that different examiners reach the same results and same interpretation of the results. Different examiners can differ in size of fingers, amount of lube used, penetration depth or the ability to digitally sense tone.

(5) The internal anal sphincter is controlled by the autonomous nervous system and thus not under conscious control, whereas the outer can be controlled voluntarily. This means that the examination procedure itself can both influence the internal and external anal sphincter, which obfuscates any clinical determination or can even make it worse for the person being forced to undergo the examination.

(6) Anal tone can be influenced by a large number of diseases, clinical symptoms, mechanical damage, surgeries and medication side-effects. These alternative hypotheses are not ruled out.

(7) Experts in medical examination from Independent Forensic Expert Group have concluded that the method is largely without value and cannot reliably be used to detect differences in anal tone that can be attributed to consensual, same-sex anal sex.

(8) Not all gay men engage in receptive anal sex and some straight men do. Thus, the predictive value of receptive anal sex for detecting gay men is limited. For instance, according to a study by Rosenberger et al. (2011), only 37.2% of the sample engaged in anal sex in their most recent sexual interaction and Bell et al. (1999) in BMJ suggests that about 2/3 of gay men engage in anal sexual regularly. Despite some variability depending on population and research questions asked, anal sex is hardly universal among gay men. It is also obvious that not all gay men are always the receptive partner, so the true figure is likely even less. It is hard to find data for what proportion of straight men take part in receptive anal penetration or anal play, but one conference paper suggested that 24% of straight men had received anal fingering from a female partner. We should not put too much emphasis on the precise figures to due the lack of data, but the general conclusion that not all gay men engage in receptive anal sex and some straight men engage in receptive anal play. This means that the method, even if it had worked (which it does not), do not have that much predictive value.

Eleven legal, ethical and moral reasons against forced anal examinations

Forced anal examinations is not only scientifically invalid and unproven pseudoscience, but there are at least close to a dozen legal, ethical and moral reasons for why forced anal examinations are wrong. These are:

(1) Having fingers inserted by force into the anus causes physical pain. This pain can be increased by unconscious increase in anal tone by stress.

(2) Forced anal examination causes psychological suffering, and can create feelings of humiliation, powerlessness, shame, guilt, self-disgust and worthlessness.

(3) These examinations are often accompanied by other forms of punishments, such as physical abuse, threats, coercion, forced nudity and physical restraints. This can further amplify the problems in (1) and (2).

(4) Other detainees can amplify the psychological negative effects when they find out and they can also abuse the subject.

(5) It can lead to discrimination, stigmatization, social rejection and mental illnesses such as depression, anxiety and PTSD.

(6) It is a betrayal by society and medical professionals, which can be worse than had it been someone else.

(7) Forced anal examinations can lead to rejection by friends, family, relatives, colleagues and work and thus a collapse of social support, employment and education.

(8) It is comparable to rape and in many countries it is considered to be rape.

(9) It violates the UN Convention Against Torture according to several UN bodies, such as the UN Committee against Torture, the UN Special Rapporteur on Torture, and the UN Working Group on Arbitrary Detention. The Office of the United Nations High Commissioner for Human Rights called for a ban on forced anal examinations. The practice is also denounced by 12 other UN agencies.

(10) It is incompatible with international standards of professional ethics.

(11) It violates the bioethical principle of autonomy.


Forced anal examinations for detecting sexual orientation or sexual behavior is bullshit pseudoscientific bigotry.


Debunker of pseudoscience.

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