Massachusetts Senator John Kerry is among the leading Democrats asking the FDA to end its ban on gay blood.

After intense lobbying from advocacy groups and lawmakers – including 2 letters to FDA Commissioner Margaret Hamburg and an op-ed written by Kerry – the Food & Drug Administration (FDA) agreed in March to reexamine its policy.

The FDA currently imposes a lifetime ban on men who have had a sexual relationship with another man since 1977 from donating blood. But the agency only excludes people who have engaged in heterosexual sexual activity with a person know to have HIV, the virus that causes AIDS, for one year.

Gay rights groups say the policy creates an unfair double standard and that it stigmatizes gay men.

A Health and Human Services advisory committee reviewing the policy will hear testimony today and Friday on the blood ban, but the FDA will have the final say.

“It's a very positive step that HHS is meeting this week to reconsider the lifetime ban on gay Americans donating blood,” Senator Kerry said in a statement. “The medical and scientific communities have been crystal clear that there is no longer any scientific evidence to warrant his policy.”

On Wednesday, Kerry, along with 42 Democrats, wrote to the advisory committee considering the policy.

In the letter, the lawmakers argue that the ban specifically singles out gay men and is scientifically unsound.

“For instance, there is no prescribed consideration of safer sex practices, individuals who routinely practice unsafe heterosexual sex face no deferral period at all, while monogamous and married homosexual partners who practice safe sex are banned for life.”

“Even individuals who have paid prostitutes for heterosexual sex face a deferral period of one year while gay men face a lifetime ban,” the lawmakers wrote. “These do not strike us as scientifically sound conclusions.”

Openly gay representatives Barney Frank of Massachusetts, Tammy Baldwin of Wisconsin and Jared Polis of Colorado are among the co-signers. Also on board are representatives Mike Quigley of Illinois and Jerrold Nadler of New York, strong supporters of gay rights.

Technological improvements in screening the nation's blood make the policy unnecessary, the lawmakers argue.

“Science, technology and education have advanced since the inception of this policy, and it's time that it, too, evolved,” Quigley said.

“Our society and its laws must move beyond the offensive and incorrect stereotype that automatically links gay men to risky sexual practices and, therefore, to HIV/AIDS,” Nadler said. “If we are serious about addressing the national blood shortage, then we must repeal the FDA's ban on gay blood donors now.”

Allowing gay men to donate blood is opposed by hemophilia patient groups. In the late 1970s and early 1980s about 10,000 hemophiliacs were infected with HIV before the agency implemented the policy.

CORRECTION: This version corrects the statement that Jared Polis did not join lawmakers in a June letter to the HHS; his name was omitted due to a clerical error.