In Parliament a South African minister of justice once called at "the Single greatest force that perverts our legal system.

In London, where he is in exile, the renowned South Africa journalists Donald Woods characterizes it as "the most humane and effective group helping the movement for change in my country."

The "it" in question is the International Defense and Aid Fund for Southern Africa (IDAF), an organization with committees in 10 countries that provides legal assistance to south Africans accused of political "crimes" and financial aid to their families.

The United States branch of the IDAF is housed in the basement of the Harvard Epworth Church in Cambridge. Though the group has no official ties to the University, its president is the Rev. Peter J. Gomes. Plummer professor of Christian Morals and Nancy Randolph, special assistant to President Bok, is a member of the board of trustees.

The IDAF was founded in 1956 to help defend 156 Black South Africa accused of treason. Its primary driving force in those days was an English clergyman. Canon L. John Collins, who raised funds in his country and elsewhere to pay for defense lawyers and to support the families of those on trial. In 1961, after one of the longest trials in South Africa history, all 156 Blacks were acquitted, largely thanks to the efforts of the IDAF.

Since, then however the government in President has significantly tightened the enforcement of apartheid laws and repressed any signs of dissent. In 1966, the IDAF was banned and has been forced to smuggle aid into the country through what Gomes, calls "cloak and dagger means."

Despite this constraint, the IDAF has continued to exert a strong influence in South Africa. During a recent testimonial dinner in Cambridge. Woods spoke in emotional terms of "the hundreds of people I know of " whom the IDAF has helped. And a Black South Africa studying in this area who asked not to be identified says the IDAF "has saved lives. Supported countless families of prisoners and proved to be a big thorn in the side of the government."

Yet as Kenneth N. Carstens, the IDAF's executive director for the United States, explains the organization cannot cite specific examples of people it has helped for fear of reprisals against those people their lawyers and their families in South Africa.

This fact of life makes the task of fundraising extremely problematic, because it is difficult to elicit funds for a cause whose effectiveness cannot be documented, Carstens says. Nonetheless, the IDAF raises millions of dollars a year that make their way to South Africa. But of the 10 national committees-England, Ireland, Canda, Sweden, Norway, Denmark, Holland, NewZealand, India and the U.S.-the American branch contributes the smallest amount, last year about $100.000.

Carstens explains that this because the U.S. government gives no support to the IDAF. By comparison, the Swedish government contributes over $ 52 million a year. "The sad truth is that the least sympathetic government of all are those of the United States and England," Carstens says. "So much for conservatives concerned for justice."

The American committee did receive one federal grant-$25.000 for one year under the Carter Administration. Now it relies on donations from individuals and foundations, including the Chicage-based MacArthur Foundation.

Still, the IDAF powerful advocates in Washington Sen. Paul E. Tsongas (D-Mass.), a member of the Senate ad hoc monitoring group on Southern Africa, is a sponsor of the organization and has worked closely with Carstens in the past. At Carsten's Suggestion. Tsongas and other members of congress "adopted" political prisoners in South Africa to whom they corresponded and lent moral support.

Gomes believes the IDAF is unique. "There is lots of talk about South Africa with little directions or forces." he says. "The IDAF provides those missing ingredients."

The IDAF, by providing funds for lawyers, serves a "priceless" function. Gomes says. Because most South Africans tried for political crimes have little money, they have difficulty obtaining lawyers. Since there is no free public defence in South Africa. The IDAF, says Gomes, defers the necessary financial stimulus.

In addition, by giving aid to the families of political prisoners, the organization helps remove a deterrent to dissent. "There is no welfare for the relatives of Criminals in South Africa." Gomes explains, "So families are punished along with the prisoner which is the ultimate form of intimidation. We negate to some extent that intimidation through financial assistance."