The age of adulthood -- and the rights and responsibilities that come with it -- is largely a matter of opinion. Age 18 traditionally separates minors from adults. But one can't legally buy a drink in America until age 21. Meanwhile, many states are now sending minors into the adult criminal justice system, even for nonviolent crimes.

Some laws make no sense. For instance, 20 states ban driving while cell-phoning, but only for those under 18. Not only is this activity dangerous for all drivers, teen brains are actually better wired for multitasking than those of 60-year-olds. Many elderly people can no longer safely operate vehicles, but no state automatically takes the keys away for reason of advanced age.

Our society's age-specific approaches often boil down to curbing the freedoms of the young -- and increasing their punishments. Such contradictions bother Brian Wilcox, director of the Center on Children, Families and the Law at the University of Nebraska.

"Sometimes we draw these lines because policy makers want to do something about an issue but don't want to offend all the constituents out there," Wilcox told me. "They take the easy route by going after young people."

Wilcox is especially wary of treating younger adolescents as adults in court. Neuroscience finds that portions of the brain are still developing up through age 25. These areas control "executive decision making," which is the ability to consider a wide range of options and consequences.

"An immature decision maker will often respond with the first course of action that comes to mind," Wilcox says. People of all ages might immediately feel anger after being provoked, but a more mature person will think through the alternatives before acting.

Teens and young adults are better prospects for rehabilitation because they are still forming patterns and habits. Wilcox points to studies showing that for teens convicted of similar crimes, those that go into the adult system are far more likely to engage in extreme criminal activity when they get out -- and end up back in jail.

What happens is that when a teen commits a monstrous crime, it is looped on the cable channels for days. The public imagines a mob of adolescent super-predators and demands they be treated as adults. Some young offenders cannot be safely released into society, of course, but the vast majority of juvenile crimes are against property.

The drinking age has long been a tug-of-war. Is a 19-year-old mature enough to fight in Afghanistan but not to order beer in a bar? Almost every other country sets the drinking age at 18.

The presidents of 135 colleges have called for lowering the drinking age from 21. They note that the age restriction hasn't stopped binge drinking on campus and argue, not without reason, that it has turned alcohol into forbidden fruit begging to be picked. Perhaps teaching young adults how to drink in moderation is the better way to go.

Rules on permissible ages to have sex have lost much rationality. In 10 states, a single 20-year-old man breaks the law by having sex with a 17-year-old. But, sad to say, many girls today have amassed considerable sexual experience before even graduating from junior high. Is a 15-year-old girl who has had numerous sexual partners to be protected from a 20-year-old male who may not have?

"In a perfect world, we'd have things designed around peoples' capacity," Wilcox said. Some 18-year-olds can drink responsibly, and some 30-year-olds can't.

In our imperfect world, the law has to draw lines, however arbitrary. But laws that only appear to address a problem by burdening young people aren't wise, and they aren't fair.

COPYRIGHT 2010 THE PROVIDENCE JOURNAL CO.

DISTRIBUTED BY CREATORS.COM

See Other Political Commentary.

See Other Commentaries by Froma Harrop

Views expressed in this column are those of the author, not those of Rasmussen Reports.