Plucked from the darkness of an El Salvador jail cell where he had been held without charges for four months, Ricardo Calderon arrived here in the glare of US news media this week offering himself as proof that American public pressure does make a difference.
Mr. Calderon, a journalism professor and secretary general at the National University of El Salvador, was released over the weekend to an American delegation representing members of Congress, the Roman Catholic Church, and international academic groups that had lobbied for his release. President Alvaro Alfredo Magaa even consented to see the delegation that had taken up Mr. Calderon's case in July, when he was kidnapped by armed men dressed in civilian clothing.
A US State Department official notes that public pressure from the United States appears to have growing influence with the Salvadorean government.
Calderon's release was the third time in less than a month that the government had released political prisoners after intercession by North American groups representing individuals rather than governments.
''It means that a sustained, broadly based effort in this country to insure just treatment of individuals in El Salvador can work,'' says Bill Kraus, who represented Congresswoman Sala Burton (D) of California in the delegation's two-week lobbying effort in El Salvador. He adds that President Magana ''was persuaded that he has to deal with public sentiment in the US,'' because his government receives controversial aid from the US.
(Though no Salvadorean diplomats at the nation's chancellery in Washington were available to discuss the Calderon case, it is reported that he was arrested for ''subversive'' leftist activity connected with his work at the university. Ironically, just prior to his arrest, Calderon had been appointed to a government commission charged with reopening the university, which was occupied by the military three years ago. Calderon and others have held classes in rented storefronts since that time.)
At a press conference, Calderon refused to detail the specifics of his prison stay except to note that he was not physically tortured, largely because his captors knew his case had been taken up internationally and he was receiving ''hundreds of letters'' of support from abroad. But he said emotionally through an interpreter that the worst torture was psychological.
Calderon, his wife, mother-in-law, and 15-month-old son were brought to San Francisco on tourist visas drawn quickly by US Embassy officials the day he was released. Attorneys who are handling his case do not know yet what formal immigration status, such as asylum or permanent residency, he will seek.
Though the Reagan administration supports the Salvadorean government, the US does grant political asylum for Salvadoreans, says Duke Austin of the US Immigration and Naturalization Service (INS).
He adds that this is not a tacit condemnation of the right-wing government in El Salvador, but merely an acknowledgment that individuals may be in danger if forced to stay in their homeland.
He says asylum is not necessarily limited to leftists in that country, because those on the right may also be in life-threatening situations that would warrant asylum, too. (Mr. Austin notes for the sake of comparison that roughly the same number of Salvadoreans were granted asylum in 1982 as Polish applicants.)
Although there are more than 13,000 asylum applications from Salvadoreans on record with the INS, about 1,000 Salvadoreans a month are apprehended at southern US borders. It is likely that many more than the number of those who apply for asylum are turned away from the US.
Meanwhile, Calderon says he and his family hope to return to their homeland, though ''not until there is a real democracy there.''