Despite many homophobic laws being lifted by the United States government, Gay individuals who have had gay sex are prohibited from donating blood. The 21 century and discrimination and the HIV/AIDS scare is over. Not only is all blood screened but major organizations such as American Red Cross and America's Blood Donation feel the rule is unnecessary, as well as the fact that the CDC has been sited saying that there is a 1 in 15 million chance that a blood donatee will receive HIV/AIDS from the donations - and NBC agrees.

http://www.nbcnews.com/health/health-news/promised-fda-lift-ban-gay-blood-donation-n357816