If capital punishment is going to be a real deterrent, says Robert Badinter, "you have to use it the way Mr. Khomeini does--not just here and there . . . but by the hundreds, by the thousands."

For his part, Badinter would rather not use it at all. He spent a decade of his life battling against the death penalty in France, and not only won the battle but also got named his country's minister of justice in the process. And he continues to believe the death penalty is a dying institution--recent developments on these shores notwithstanding.

"Paint in red the countries where the death penalty is used and in white the countries that are liberated from it," Badinter told an Amnesty International luncheon at the Capital Hilton yesterday, "and almost country by country you will see that the map of freedom and the map of abolition of the death penalty fit exactly together--with a few exceptions."

But he seemed to have only one exception in mind--the United States, where five men have been executed since 1977, and a sixth execution was postponed by a Supreme Court order issued Monday.

"In peacetime, I do not think of another democracy practicing the death penalty," Badinter said Monday evening in an interview at the residence of French Ambassador Bernard Vernier-Palliez. "Of course, I'm not speaking of the countries where vice plays tricks with virtue by saying it's a democracy when it's not."

As ministers of justice go, Badinter has to be considered one of the world's more unusual.

Softspoken, handsome and a stylish dresser, he entered government at the age of 53 in 1981, when the socialist regime of Franc,ois Mitterrand came to power. Before that, he had been a lawyer specializing in copyright, press and motion-picture cases, and a law professor at the University of Paris.

He was the child of Russian e'migre's who had settled in Paris. His father was a successful furrier until World War II, when he and other members of the Badinter family perished in Nazi concentration camps. Later, Badinter studied sociology at Columbia.

His interest in the death penalty dates back to 1972, when he saw one of his own clients executed. "I was against capital punishment as most lawyers and most intellectuals of my generation in France are against death penalty," he recalled, "but I didn't make it an issue in my life." Then "a friend of mine called me to defend with him a terrible crime"--a prison hostage-taking in which a guard and a nurse were murdered--"and I won and lost the case."

He won in that the court agreed that another man, not his client, had done the actual killings. He lost in that his client was convicted as an accomplice--and executed.

"I saw him cut in two pieces in front of me," said Badinter, turning away further questions about that experience with the comment that "I never go into details. Never."

The guillotine's status as the traditional tool of French executions dates back to the 1790s and the Reign of Terror. It had an egalitarian appeal, according to Badinter, because kings were always beheaded while commoners had previously been hanged. "So it belonged to the history of the republic. But I remember when criminals were shot after the war. Whatever the instrument, it makes no difference."

During the last French election campaign, a retired assistant executioner, Georges Perruchot, caused a stir by revealing that the guillotine had not always performed as efficiently as people assumed. Once, he told a magazine interviewer, a head had been left hanging and had to be severed with a knife. "You are a little splashed with blood sometimes," he said. "You have to go clean up."

After the execution Badinter witnessed, he wrote an attention-getting book about the case, "L'execution," and proceeded to defend six more men who faced the death penalty. "And I was happy enough to save all," he said. And his success provided additional ammunition for the effort to end capital punishment completely.

While one man had been "executed without being guilty," he said, another "who had committed the most terrible murder--killing a kid and then collecting a ransom from the parents after the murder--he got off. We cannot accept morally that such a mass of uncertainty leads a man to be executed . . . What strikes a man to the heart is the fact that to support death penalty, one should have une justice infallible, which is not human . . ."

Before the last election, Mitterrand was asked about capital punishment in a television interview, and he quietly replied that he was against it and hoped, if elected, to end it. That, according to Badinter, was "a very important moment" in the campaign. Although French public opinion generally supported the death penalty--and still does--Badinter said the voters were impressed by this "fundamental moral approach by a major leader."

In the year and a half since the French Parliament voted to end the death penalty, there has been no increase in kidnapings, murders of police officers, or homicides in general, according to Badinter. In fact, homicides have remained at about the same level in France for the last 30 years.

"Violent crime follows its curve unaffected by the presence or absence of the death penalty," he said. "You find nowhere any study, any evidence, on the other side."

He concedes that public opinion tends to believe otherwise, and in France the sentiment for capital punishment inevitably rises after headline-grabbing incidents of rape, murder or terrorism. But "the scared do not know reason."

In any case, the western countries with the worst terrorism problems--West Germany, Italy and Israel--have not moved to reinstate the death penalty, Badinter said. And he recalled being told by an Israeli official that "in the eyes of some and especially among the young, the execution of a terrorist gives him a heroic dimension."

On the day the French Senate (still under conservative control) cast its final vote against the death penalty, "I was alone," said Badinter, "and I walked through the garden and I sat down--it's a beautiful place--and I felt this was finally over. I confess to you, I never think of the death penalty anymore, but in the United States you have brought me back."