. >> reporter: under the law, judge paul cassell was forced to do something that burdens him still. >hink about him? >> i do think about angelos. i drive on the interstate by the prisoner what he's held. i think, that wasn't the right thing to do and the system forced me to do it. >> reporter: under federal mandatory minimum sentencing laws angelos was facing 55 years for the gun and marijuana charges combined. he was a first-time offender. >> mandatory minimum is a sentence that says the judge has to impose a particular minimum number of years. it ties the judge's hands. >> it was designed during the reagan administration's war on drugs to send a message, right, to drug dealers this won't be tolerated. >> so mandatory minimums can be used to send a message. but at some point the message gets lost. >> reporter: paul cassell has since retired from the bench to teach law but says the angelos case weighs on him. the reason he agreed to speak about his ruling, something federal judges almost never do if he had been an aircraft hijacker he would have gotten 24 years in prison. if he'd been