Four Harvard professors have added their signatures to a recent letter criticizing General Barry R. McCaffrey, the director of the White House Office of National Drug Control Policy, for disregarding evidence that they say challenges his hard-line drug policies.

The professors who signed the letter are W.E.B. DuBois Professor of the Humanities Henry Louis "Skip" Gates Jr., Clinical Professor of Psychiatry Dr. Alvin F. Poussaint, Cowles Professor of Sociology Orlando Patterson and Geyser University Professor William Julius Wilson.

San Francisco Mayor Willie L. Brown Jr. and former Surgeon General Joycelyn Elders, as well as several other public health advocates also added their names.

The Feb. 24 letter, circulated by the drug policy reform organization Common Sense for Drug Policy, argues that McCaffrey has ignored studies showing the medical benefits of marijuana smoking and the success of needle exchange programs. It also charges that McCaffrey used faulty data in comparing U.S. and Dutch drug policies.

McCaffrey has been a vocal opponent of the medical use of marijuana and of needle exchange programs, which, according to the letter, he called "magnets for all social ills" in March 1998.

"As academics, journalists, public health experts, and community leaders, we are deeply troubled by a series of inaccurate and misleading statements you have made as Drug Czar," the letter reads.

According to the letter, McCaffrey said the murder rate in Holland is "double that in the United States" due to the prevalence of drugs in that country.

"In fact the Dutch homicide rate is only one-fourth that of the United States," the letter contends.

McCaffrey has responded to the letter, saying he plans to send an aide to speak with the group, according to a story in yesterday's Los Angeles Times. In the article, he denied distorting drug data, stating that the letter only represents "different, legitimate viewpoints."

Poussaint said support among Harvard professors for sending McCaffrey a letter grew in June, when the Harvard AIDS Institute hosted a conference called "Leading For Life" in coordination with the W.E.B. Du Bois Institute.

Participants at the conference discussed the high rate of HIV infection among black Americans and debated the effectiveness of needle exchange programs.

According to Poussaint, McCaffrey's stance on the needle exchange issue was the major impetus for the letter.

"In a lot of his public statements [McCaffrey] ignores scientific evidence," Poussaint said. "He goes with his moralposition, thinking that needle exchange sends themessage that the United States condones needleuse."

"We thought we would publicly fight back," hesaid.

But Robert L. Maginnis, the senior director fornational security and foreign affairs at theFamily Research Council, a Washington basedthink-tank, said there is conflicting evidenceregarding needle exchange and medical marijuanause. He said the latest studies support McCaffrey.

"Over the last three years, the best controlledstudies have really brought a lot of skepticism tothe argument that needle exchanges are the way togo," Maginnis said. "There were many problems withprevious studies."

Maginnis also said McCaffrey does not disputethe claim that marijuana has certain medicalbenefits.

"But in America, we have the medical resourcesto deliver the beneficial ingredients without theneed to smoke crude marijuana," Maginnis said