You cannot see the prisoners' faces because paper-bag blindfolds cover their heads.

No, this is not a scene from Iraq's Abu Ghraib prison. It is a scene from a makeshift prison in the basement of a Stanford University building in August 1971.

The "guards" and their "prisoners" were college students and other young men who responded to a newspaper ad that offered participants $15 a day to take part in an experiment on prison life. The study was funded by the Navy and conducted by psychology professor Philip G. Zimbardo to help explain conflict in military prison systems.

The famous and controversial Stanford prison experiment, which now has its own Web site (www.prisonexp.org), is worth remembering as the Bush administration publicly condemns torture, yet balks at making its use illegal. Before it was over, the Stanford experiment showed how even a group of guards and prisoners handpicked as "most stable [physically and mentally], most mature and least involved in anti-social behavior" can revert, as in George Orwell's "Animal Farm" or William Golding's "Lord of the Flies," into guards-gone-wild.

The experiment, planned for two weeks, was shut down after six days. By then, the civilized, well-educated guards had degenerated, despite frequent warnings to refrain from violence or humiliating tactics. Among other abuses that ring with eerie familiarity these days, Stanford's volunteer prisoners were forced to clean toilet bowls with their bare hands, sleep on a concrete floor without clothing, go without food, endure forced nudity and engage in suggestive sexual acts of a homosexual and humiliating nature.

The Stanford experiment came to the minds of many experts after photos from Abu Ghraib prison revealed similar abuses were being committed there under the authority of American armed forces. Whether the guards at Abu Ghraib behaved out of individual character flaws or by direct orders from the Pentagon, as reporter Seymour Hersh alleged in The New Yorker, the Bush administration officially deplores such behavior.

Yet, curiously, President Bush has threatened to veto a measure, backed by Sen. John McCain (R-Ariz.) and overwhelmingly passed by the Senate last week, that would prohibit the "cruel, inhuman or degrading treatment" of prisoners in the custody of the U.S. military. Current Bush administration policy puts the U.S. in an awkward situation. The binding international Convention Against Torture prohibits cruel, inhuman and degrading treatment.

But the administration argues that the law does not legally apply to foreigners that America holds outside the U.S. Does that mean that foreigners held outside the U.S. can be treated in a cruel, inhumane and degrading manner? Why, then, did we court-martial our guards-gone-wild at Abu Ghraib? McCain proposed to close the loophole and end the confusion with an amendment to a defense appropriations bill that would prohibit the cruel, inhuman or degrading treatment of prisoners in U.S. military custody.

Having endured beatings and two years of solitary confinement during his 5 1/2 years in Vietnam's infamous Hanoi Hilton prison camp after his Navy fighter jet was shot out from underneath him, McCain knows a thing or two about prisoner abuse. Among other things, he learned that countries that allow torture during prisoner interrogation lose more in moral standing worldwide than they gain in useful information.

This is especially true of countries that allow torture while telling the world that they don't. Since Bush holds the record for having served the longest in the White House without vetoing any legislation, breaking his streak on an anti-torture measure would send an awkward message to the world. It also sends a contradictory message to our troops that says we'll look the other way on torture, unless you get caught.

While the Senate debated McCain's bill, by coincidence, professor Zimbardo's scientific work received an award for its contributions to cultural enrichment from the Dagmar and Vaclav Havel Foundation in Prague. The House and Bush could further enrich humanity by passing and signing McCain's bill.

Our troops in Iraq, Afghanistan and Guantanamo Bay in Cuba certainly do not torture and kill with the blood lust that Saddam Hussein and our other terrorist enemies do. But a great nation should measure itself by higher standards than that. Clarence Page is a member of the Tribune's editorial board.