In his focus on prosecuting the "worst of the worst" offenders, U.S. Attorney B. Todd Jones has dusted off a 1934 law intended to thwart labor racketeering and extortion by gangsters such as John Dillinger.

The Hobbs Act carries long, mandatory prison terms and can be used nearly any time someone uses a gun to rob a business that has anything to do with interstate commerce. Federal prosecutors say they use it to target gun-toting career criminals.

"We're looking at hardened criminals," Jones said. "These are not first-time offenders."

Court records show that on Jones' watch, 29 defendants have been charged under the act, compared to just four Hobbs cases from 2006-2009.

The 15 defendants sentenced so far got an average of 15 years in prison. The mandatory sentences can give a judge pause.

U.S. District Judge Donovan Frank criticized the use of the Hobbs Act against Theodore Collins, a 26-year-old single father who had a job and no record of felonies, violent crimes or drug offenses.

Collins bought a gun in 2010 and let a cousin with an extensive criminal record use it to rob a gas station. They were caught as they drove away. Collins immediately admitted his guilt and was charged in Hennepin County. Then federal prosecutors stepped in.

Collins initially agreed to plead guilty to a related charge that could yield a sentence of about four years. But a supervisor overseeing federal gun cases insisted that he plead guilty to violating the Hobbs Act, which carried a minimum seven years. Collins had to accept, or risk more time if convicted.

Frank called the sentence "a miscarriage of justice." He said he probably would have given him three years or less.

Thomas Hollenhorst, assistant U.S. attorney, told Frank his office makes no apologies.

"We are in this business to deter this crime and to prevent crime. ... We want the bells to ring clear and loud ... even if a defendant is a one-time offender, no criminal record, loves his kids, has a good support system with his family."