Prosecutors have sound reasons for wanting more power to decide when juveniles should be tried as adults: a rising tide of heinous violent crime committed by kids; a public made increasingly irate by remorseless repeat offenders and wrist-slapping judges.

Opponents, largely defense attorneys, also make a good case. Many of our worst young criminals are themselves victims of abusive and neglectful childhoods. They need help, not hard time.

But before the Legislature steps into this emotional morass, it would do well — after giving the competing horror and sob stories fair hearing — to remember that its fundamental task is to protect the interests of the law-abiding public. Its obligation to criminals — juveniles or adult — is not to give them a second chance, but to give them a chance to earn a second chance.

To that end, lawmakers should take a skeptical view of the shopworn argument that sending a 17-year-old rapist to prison for five years merely results in a 22-year-old with more developed criminal skills. If that is so, if the adult prison system inevitably produces nothing but career criminals, there can be no moral justification for any sentence, for any crime, other than life without parole. If it is wrong for a teen to be condemned to a life of crime, it is just as wrong for a 20- or 30-year-old, and it is unconscionable to unleash these state-trained monsters back upon society.

Clearly, that is not the case. It is likely that most convicts leave Maine’s prison system better off than they entered — with better reading and writing abilities, better job skills, a better understanding of the sanctity of another person’s life and property. Before it makes any decision, the Legislature should demand from the Department of Corrections the best accounting possible of the course taken by those released from prison; how many go on to productive lives, how many revert to crime. This decision must be based upon the rule, not the exception.

As for the exceptions, the repeat offenders, the Legislature should change the law that now expunges a juvenile crime record upon reaching adulthood. As most police officers and prosecutors will attest, far too many young criminals laugh at the black marks they compile, knowing the slate gets wiped clean upon reaching adulthood. Certainly, the indiscretions of youth — minor pranks and lapses of judgment in which no one was hurt — should not be a lifelong blemish, but crimes of violence, crimes that would be prosecuted as felonies if committed by adults — should not vanish simply because of an 18th birthday.

The prosecutors are asking that the law be changed so it becomes the responsibility of the juvenile defendant and his or her attorney to show why a serious, grownup crime should not be prosecuted in the grownup world. Society has shouldered the weight of juvenile crime long enough; it’s time for the Legislature to place the burden where it belongs.