A former federal judge told ABC News that he regrets sentencing a man to 55 years in prison for multiple nonviolent drug deals involving marijuana — but mandatory minimum sentencing laws left him with no choice.

In 2002, police caught Weldon Angelos selling marijuana while allegedly possessing a firearm in three separate stings. Federal prosecutors stacked each of these stings into three offenses, with all the charges adding up to a 55-year minimum prison sentence with no chance of parole. Once Angelos was found guilty, the judge had to hand down this minimum sentence, regardless of his views.

Paul Cassell, the retired Utah judge who tried Angelos' case, said the sentence haunts him to this day: "I do think about Angelos. I sometimes drive on the interstate by the prison where he's held, and I think, 'That wasn't the right thing to do, and the system forced me to do it.'"

Marijuana is actually one of the least penalized illicit drugs under federal law, according to Families Against Mandatory Minimums (FAMM). Someone would need to sell 1,000 kilograms of marijuana to get a mandatory minimum sentence of 10 years in prison, but it would take only 1 kilogram of heroin, 5 kilograms of powder cocaine, or 280 grams of crack cocaine to trigger a similar penalty.

These mandatory minimum sentences were enacted in 1986 as part of the federal government's escalation of the war on drugs. The idea was to send a clear message to drug dealers, particularly at the height of the crack cocaine epidemic, that illicit drug trafficking wouldn't be tolerated.

But Cassell, who was appointed by former President George W. Bush, said the punishment can go too far, as Angelos' case demonstrates. "It ties the judges hands," he said. "At some point, the message is lost." He added, "If he had been an aircraft hijacker, he would have gotten 24 years in prison. If he had been a terrorist, he would have gotten 20 years in prison. If he was a child rapist, he would have gotten 11 years in prison. And now I'm supposed to give him a 55-year sentence? I mean, that's just not right."

Angelos' lengthy punishment is a result of enhanced sentences: mandatory minimum sentences can be expanded further if police find a drug dealer to be in possession of a firearm. What's worse, this enhanced penalty applies even if someone is found to have a legally purchased and registered gun or rifle in their home or car — even if the weapon wasn't present or used during the drug dealing offense, according to FAMM.

Many criminal justice experts already argue mandatory minimum sentences are far too long even without firearm possession enhancements. The Obama administration has supported legislation that would loosen mandatory minimums. Other groups, such as the Drug Policy Alliance, have called on the federal government to go further, and decriminalize all drugs and legalize marijuana.

Without reform, the only hope for people caught in situations similar to Angelos' is that the president will commute or pardon their sentence.