There was a time when Americans who traveled abroad could count upon the protection of their government. Today, almost any foreign potentate can drag them off to his torture chambers and prisons without a worry about retallation.

For President Carter's crusade for human rights doesn't seem to apply to the 2,200 Americans who are serving time in dismal prisons from Bangkok to Bogota. Their rights are supposed to be protected by the consular officers, who are attached to U.S. embassies.

It is the theory of the American system that the government is supposed to serve the individual. This principle is set forth in noble language in the consular officers' official handbooks. They are reminded that "neither arrest nor conviction deprives a United States national of the right to the consul's best efforts."

The consular officers are sworn to look after the citizen's "welfare and defense," to protect his "legal and human rights." Declares the handbook: "Like attorneys and social workers, consular officers are obligated to serve their clients with dedicated professional enthusiasm regardless of their own opinions of the client's innocence or personal merit."

That's what the handbook says. In practice, many consular officials are more interested in preserving their cozy relationships with their hosts, including dictators and despots, than in upholding the human rights of American citizens. Americans who fall into the clutches of foreign police have learned to expect no more than a polite murmur of protest from the State Department.

The Americans who take the worst abuse in foreign jails are young drug offenders, many of whom were caught with no more than a few pinches of marijuana. Others were arrested for attending parties where pot was smoked, although they did not partake.

They are in prison because their own government, in its zeal to halt worldwide drug traffic, brought tremendous pressure on various governments to crack down on drug violators. The dragnet caught few smugglers but many users.

We have interviewed dozens of these youthful offenders and their parents. We have heard tale after tale, sincerely rendered, of the denial of basic rights: beatings, threats, extortion and expropriation of personal property. In many countries, the American consular officers have been only grudgingly cooperative; some have even sided with the tormentors against the Americans.

On Jan. 1, we turned the spotlight on three dozen American prisoners who were confined in bleak Bolivian jails. Several swore they were guilty of no more than minor misdemeanors or were innocent altogether. They sought the protection of the U.S. embassy but got the brush-off from a consular officer named Edward Milburn.

The parents appealed to their congressmen, who wrote a joint letter to Secretary of State Cyrus Vance. What is of particular concern, they complained, "is the apparent failure of our embassy personnel to take action - or display much sympathy - on behalf of these prisoners."

All too typical is the attitude of Richard Schenck, the U.S. consul in Caracas, who complained about our column in support of the incarcerated Americans in Bolivia. "I am rather tired," he wrote on embassy stationery, "of the current 'namny-pamby' solicitude for these [drug] users and traffickers. They are not all hardened criminals, but almost all are dropouts and non-contributors looking for cheap junk."

This same Schenck, incidentally, is employed by the American people to protect their rights in Venezuela. A dozen Americans in Venezuelan jails must depend upon him for relief.

The American consul in Chile, Fred Purdy, secured the release of Amy Conger, an American art teacher, after she had been badly abused and molested by military police. Her release was handled quietly, without a word of protest from the State Department. When we finally published her story, Purdy spoke up in support not of Amy Conger but of her Chilean torturers.

In contrast, when a British national, Dr. Sheila Cassidy, was abused by Chillean officials, the British government secured her release, withdrew its ambassador from Chile and issued a stinging statement.

In Bolivia, British consul British consul Brian Barrett always appears immediately after the arrest of a fellow countryman. He usually succeeds in arranging to have the British citizen deported rather than left to rot in Bolivian jails.

In Thailand, according to a letter from American prisoners, American consular officer Robert Jacobs visited their jail and pronounced it "better than a lot of prisons." Then British officials came by, called the place a "stink-hole" and arranged for the transfer of British inmates to a better prison.

There are, of course, many U.S. consular officers who are concerned and compassionate.

In Guadalajara, Mexico, Consul Gen. Mathias Ortwein became worried about the safety of American prisoners after an outbreak of rioting. He used his personal influence with Mexican authorities to arrange for the transfer to the Americans to another facility.

Ruth Matthews, the U.S. consul general in Mazatlan, Mexico, has made an enormous effort to defend the interests of American prisoners. And Vernon McAninch, who was summoned to Mexico from the Dominican Republic, requires a minimum of one visit per month to Americans in prison.

But many consular officers, unfortunately, seem to have forgotten their first duty.