Most gay men in most Western countries are banned from donating blood for life. The screening test for donors on the website of the National Blood Service for England and North Wales, for example, asks, “Are you a man who has had oral or anal sex with another man (even if you used a condom)?” Answering yes results in an automatic no thank you.1

Men who have ever had sex with men are also excluded from donating blood in most other European countries and in the United States2 and Canada,3 but several developed countries have alternatives to permanent, blanket bans—for example, Spain, Australia, and New Zealand.

Outright bans have become increasingly controversial, and in February the gay rights group Stonewall changed its position after a two year review and called for the UK blood services to apply the same risk assessment to homosexuals as it applies to heterosexuals.4 Last November the Scottish parliament rejected a petition supported by Amnesty International to revise the ban in Scotland.5 6

Blood services introduced policies of “lifetime deferral” in the 1980s, soon after the start of the AIDS pandemic, to try to protect the blood supply from infections that can be transmitted through blood transfusion, such as HIV. Although blood services test donations, screening is fallible. The public expect total safety and after the infection of many haemophiliacs with HIV and hepatitis C through transfusion, blood services are wary of any changes in policy that might increase rates of transmission.

UK health ministers are advised on blood safety by the independent Committee on the Safety of Blood, Tissues, and Organs, whose members include doctors and …