(CBS) — The head of a prison watchdog group says the prevalence of mandatory minimum sentences for many crimes is driving up the cost of our criminal justice system, and not doing society much good either, reports WBBM Political Editor Craig Dellimore.

Many elected officials, including Mayor Rahm Emanuel, want to see mandatory minimum sentences for things like gun crimes. They hope it will act as a deterrent.

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But, Jennifer Vollen-Katz, executive director of the John Howard Association, says mandatory minimums are one reason why our prisons are so overcrowded.

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“The longer you send people to prison the longer people stay in, the more crowded you become and mandatory minimums leave very little room for discretion so even if a judge sees qualities in a defendant that indicate they may not be a risk to themselves or others, that this may be a one-time huge mistake and certainly there should be some consequence but that a long term of imprisonment is not the appropriate one, their hands are tied,” she said.

But Vollen Katz admits, some officials and the public fear letting the wrong person out. She says that’s an unrealistic reason to stay with the status quo.

A state commission is examining sentencing reform, but issues like this will be contentious.

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Vollen Katz was a guest on our At Issue program. To listen to the full program, click here.