China is beginning to move toward a more equitable legal system, with public trials and trained defense attorneys, but lengthy conversations here recently revealed a great gap between popular demands for more human rights and the policy of the Communist Party.

In a wide-ranging exchange with American journalists, two law experts from Peking University refused to concede that China's most famous political prisoners -- the infamous Gang of Four -- had any right to a speedy or open trial until the party decided it was time for one. As the Carter administration prepares to discuss its human rights concerns again with visiting Vice Premier Teng Hsiaoping, the chance for any real understanding on such matters seems slight.

Instead, the Chinese seem to be trying to patch up, bit by bit, a legal fabric ripped to shreds by two decades of political typhoons.

Trials are opening to the public again, except in cases of national security or sexual offenses. Universities are training lawyers to replace amateur defense counsels, now usually a friend or relative of the accused. People at the bottom, even political outcasts like former landlords, are being given hope of fairer treatment, but high political criminals like the Gang of Four are still considered beyond all rules.

The "gang" comprises four former Politburo members, led by Chiang Ching, the widow of Chairman Mao Tse-tung, who were arrested on Oct. 6, 1976, for allegedly trying to take over the government.

Prof. Shen Chung-line and lecturer Wu Ji-ying, both of Peking University's law faculty, confirmed here that no criminal charges have been filed against the four and they have not had a trial. Yet, the two law experts insisted that their arrest was justified because it was "the will of the people."

"How did anyone at the time know it was the will of the people?" an American asked. It took much of the rest of the morning to arrive at an answer vaguely comprehensible to minds used to Western standards of law. It was the people's will because people supported the arrests after they were made.

Earlier arrests and purges, such as those suffered by Vice Premier Teng, turned out not to be the people's will because people did not support them after they had been announced.

The party is the representative of the proletariat and "the law is the embodiment of the party's policy," said Shen. Despite the moves toward reforms, the law remains only what the party say it is.

"They are trying to avoid the worst abuses of the nightmare of the last several years," said Harvard Law School Prof. Jerome A. Cohen in an earlier interview in Hong Kong. "They are trying to get back to 1956, when people had a minimal kind of security. It's not free speech, but at least it's better than they've had lately."

The party has not given up its power to administer justice as it sees fit, but it has decided to administer it with a lighter hand, in hopes that both morale and economic production will increase. Peasants and workers complaining of discrimination and hunger are allowed to march in Perking apparently without anyone being arrested so far. Three men arrested in 1974 for a prodemocracy wallposter in Canton, written under the pseudonym Li Yi-che, have been released in the last two weeks, according to a report by Agence France-Presse.

A Dec. 3 article in the Kwangming Daily, a Peking newspaper aimed at intellectuals, even called for legal limits on "inner party struggles," which have filled Chinese jailes in the past with political prisoners.

Shen seemed unwilling to tread too far into this domain of the party, other than to say that "I personally would like to see a public trial of the Gang of Four."

In some areas, official broadcasts call for harsher justice, quite the opposite of what many of the appeals from friends and relatives of prisoners in Peking are saying in wallposters here.

"Some immature young people do not have the slightest impression of law and discipline and cannot distinguish between right and wrong or good and evil," the People's Daily complained last month in an article that revealed a serious outbreak of juvenile crime. A Kansu provincial broadcast said "criminals have not been dealt blows vigorously."

The campaign for more vigorous justice is called "maintaining public order and establishing good social order." Some officials have tied it to the legal reform effort by arguing that order can be restored only when everyone knows what the law is.

The lack of a widely disseminated criminal code in recent years allowed some political leaders to arrest people on flimsy pretexts. Many police stations in Canton and other Chinese cities have recently posted specific criminal statutes outside their doors.

The People's Daily has proposed giving legal protections even to people like former landlords, who have been subject to official discrimination since the Communists took power in China i 1949. This means rewriting the concept of class struggle as the Soviet Union did during the post-Stalin reforms.

Official "procurators" are now being reestablished in every locality to weigh evidence and throw out dubious police cases before going to trial. Shen and Wu said they are also trying to train as many people as possible to serve as public defenders.

The Chinese system still continues to emphasize confessions. Suspects know punishments will be lighter and their chances better if they simply admit to the charges, and give up any effective defense. Wu denied, however, that police carried this to the extreme of saying, "you will be released immediately if you confess, or if you don't confess, you will be punished severely."

Political criminals, the professors indicated, will be treated generously. Chinese sources report that one of the Gang of Four, Chang Chun-chiao, is now in a hospital being treated for cancer. Others are under house arrest, waiting to see what the party decides the law in their case should be.