In the early years of AIDS, when many people thought a deadly disease dubbed "the gay cancer" might be transmitted via drinking glasses or doorknobs, Congress added HIV to the list of infections that could prevent a foreign visitor from entering the country. Nearly two decades later, as the international Gay Games begin in Chicago this weekend, the law still bars any HIV-positive foreigner from visiting the U.S., whether it is to play basketball, attend a business meeting or stand up in a family wedding. Though immigration officials have granted a waiver to allow athletes to attend the games--just as...