From his prison cell, the criminal wrote to D.C. Superior Court Judge Ronald Wertheim, who would be issuing a sentence in two weeks. The letter--long and well-written--told of the five convictions and five prison terms the 33-year-old street hoodlum had undergone since he took to heroin as a high school senior.

"I am already considered a career criminal by the government," he wrote, "and the bottom line is unless I rid myself of this drug dependency trait I will become extinct either in rotting away in a prison or I will die from an overdose or an infected needle in a gutter on some dirty dark street."

The letter ended with a plea that Wertheim consider an alternative sentence. Instead of prison, the criminal asked to be placed in a facility called Second Genesis. It is a residential therapeutic program of proven value that provides individual counseling, group therapy, educational and vocational services. It lasts up to 24 months.

The judge took the hard line. He placed the prisoner on five years' probation and sent him to Second Genesis.

That isn't the conventional definition of hard-line justice. But sending this five-time loser to a treatment program requires a rare kind of toughness: from the enrollee, who must reach into his gut and face himself as never before, and from the judge, who must have the steel to resist the fraudulent and popular notion that the more we lock away criminals for longer sentences the safer we are.

Nothing is hard-line about the so-called get-tough judges who think jail is the only punishment and stiff sentences the only justice. They deal in weakness. They put off to another time and probably for another court the obligation of treating the criminal as something other than a hopeless case. They postpone until another day the danger created when the offender is released as a greater menace than when he went in. About 98 percent of the current inmate population of 400,000 will eventually be released, most of them the worse, from prison.

The easy-liners want to throw money at the problem: build more prisons at construction costs that can reach $80,000 per inmate, imprison the inmates at $14,000-plus a year, while a program like Second Genesis costs about $7,000 a year per person.

Judges who take the hard approach to crime and justice--rejecting high-cost punishment that creates what Chief Justice Warren Burger calls "systems of corrections which do not correct"--deserve much praise. Their views also deserve attention, which is what Attorney General William French Smith gave them recently.

In a speech refreshingly thoughtful in parts, Smith discussed alternatives to prison: "We must recognize that we cannot continue to rely exclusively on incarceration and dismiss other forms of punishment." Smith said the Reagan administration is "studying alternative forms of punishment for nonviolent offenders that will deter criminal behavior and reduce the chance that an inmate will return to criminal activity, without placing an unnecessary burden on the taxpayer."

Others have said this often. Programs involving restitution, community service, halfway houses and therapy are successful in all parts of the country. The special force of Smith's unexpected support of alternatives to imprisonment is that he can't be passed off as a turn-'em-loose coddler.

Smith is asking the question that conservatives, in their preening, like to think they are best at raising: Are we getting our money's worth?

From our prisons and jails, no. Studies have repeatedly documented that increased rates of imprisonment do not lead to decreased rates of crime. Yet the federal Bureau of Prisons gets a fiscal pampering that not even the Pentagon enjoys: an annual 10 percent increase for its operating budget, with few questions asked. The Reagan administration's 1984 budget asks for the largest increase ever for more prison space: $103 million. Most liberals not only aren't protesting, but are issuing simplistic calls, as did Walter Mondale in announcing his presidential candidacy, that "convicted criminals go to jail again."

Officials like the judge sentencing the addict-hoodlum to Second Genesis know that the recidivism rates are greatly lowered when alternative programs are used. The National Center on Institutions and Alternatives reports follow-up studies of a sample of 1,000 offenders in alternative programs: only 15 percent have been rearrested. For the imprisoned, double and triple those rates are common.

Tough judges are as needed as tough attorneys general: To get on with the hard work of explaining the uselessness of prisons as the only form of punishment.