In 1977, British TV talk show host David Frost landed the coup of the decade: a series of sit-down interviews with disgraced President Richard Nixon. The interviews were to cover a wide range of topics, including Mr. Nixon’s hindsight on Watergate, the scandal that ended in his resignation. The result was some of the most compelling, yet frustrating television ever witnessed. The former president was less evasive than viewers may have expected, and though much of his retelling of the events that led to his downfall could be characterized as spin, Mr. Nixon did make concessions about his errors in judgment.

Yet when Mr. Frost asked the ex-president if he owed the American people an apology, Mr. Nixon came close, but ultimately stopped short of saying he was sorry.

The interviews are the subject of an acclaimed Broadway play, “Frost/Nixon.” In an essay inspired by the play on Slate.com, writer David Greenberg concludes that Mr. Nixon, despite the glowing image as wise elder statesman that radiated over his funeral, was never fully rehabilitated. In the eyes of most Americans, Mr. Nixon remained in a state of unforgiven sin. One wonders how that might have changed if he had been forthcoming with a sincere, unequivocal apology.

Skeptics and cynics may dismiss the sort of public apologies to victim groups that seem to have become de rigeur for governments and institutions. For one thing, the apologies usually come long after consensus has been reached that the acts need apologies; at this point, little courage is needed to apologize to blacks in America for slavery. And, the cynic may suggest, the apology may be more of a spiritual balm for the oppressor’s guilt than a plea for forgiveness.

Nevertheless, a public apology seems to have a cleansing affect. It never wipes clean the slate, but it confirms for the aggrieved group that yes, the perceived injustice was real.

Last month, the Canadian government apologized to Native Canadians for forcing 150,000 of their children into government-financed boarding schools where many suffered sexual and physical abuse. And earlier this month, the American Medical Association issued an apology to black doctors who were essentially barred for decades from AMA membership.

Some apologies are sought but denied. In 1995, 50 years after the U.S. dropped nuclear bombs on Hiroshima and Nagasaki, Japan, President Clinton said no apology was owed. He was right; the world may regret the start of the nuclear era, but Japan refused to surrender in a war it undeniably started.

In some ways, the Catholic Church apologizing for the priest sex abuse scandal promoted healing, while to some eyes, it re-opened wounds.

The ceremony earlier this month in Bangor marking the 1984 death of Charlie Howard, an openly gay man who drowned after three teens threw him from a bridge into the Kenduskeag Stream, was a kind of apology by the community. To its credit, the immediate public outrage 24 years ago to the death served as a more timely apology.

The trick, it seems, is seeing the injustice for what it is in the present, and not needing decades of hindsight. Failing that, an apology has its place and its power.