Jeff Jacoby
IN A COLORADO TOWN in 1996, Verle Mangum bludgeoned Janet and Jennifer Davis to death.

Janet, a 42-year-old nurse's aide, had come home from work and discovered Mangum, then 17, having sex with her 11-year-old daughter, Jennifer. When Janet reached for the phone to call the police, Mangum picked up a baseball bat and fatally bashed her with it. He then used the bat to murder Jennifer as she cowered in the bedroom.

A jury eventually convicted Mangum of both murders. Under Colorado law he was given a mandatory sentence of life in prison without parole. In 2007, when the convictions were upheld on appeal, the prosecutor expressed relief. "This was one of the most heinous crimes in the history of our community," District Attorney Pete Hautzinger told the Grand Junction (Col.) Free Press. "It is very gratifying to know for sure that he will be staying in prison for the rest of his life."

But that's no longer a sure thing -- not after the Supreme Court's 5-4 ruling in Miller v. Alabama last month that the Eighth Amendment's ban on "cruel and unusual punishments" does not allow states to mandate life without parole for murderers who were minors when they committed their crime. Mangum, like at least 2,000 other juvenile killers serving mandatory life terms, including more than 60 in Massachusetts, will now have to be resentenced. The families of murder victims nationwide have now lost the reassurance that their loved ones' killers would never be turned loose. Survivors may be forced to testify all over again. There is no telling how many monsters like Mangum will end up serving less -- perhaps much less -- than the life sentence the judge and jury imposed.

Hautzinger, outraged by their decision, said its impact would be "inhuman." And when Mitt Romney held a town-hall meeting in Grand Junction last week, the DA showed up and asked him to comment on what the Supreme Court had done. But Romney sidestepped. He said only that he would "look at the particular case," and that he favors "swift and severe punishment" for serious crimes.

What Romney should have said was that the court's ruling was illogical and indefensible -- a textbook case of justices turning their personal preferences into constitutional commands.

Jeff Jacoby

Jeff Jacoby is an Op-Ed writer for the Boston Globe, a radio political commentator, and a contributing columnist for Townhall.com.