Sen. Rand Paul (R-Kentucky). AP/Charlie Neibergall Presidential candidate and Sen. Rand Paul (R-Kentucky) blasted former Secretary of State Hillary Clinton on Monday over her husband's record on criminal justice reform.

According to The Hill, the libertarian-oriented senator spoke in Philadelphia, Pennsylvania, vowing to compete in the city if he becomes the nominee.

"I'll ask Hillary Clinton, 'What have you done for criminal justice? Your husband passed all the laws that put a generation of black men in prison.' Her husband was responsible for that," Paul said.

Both Hillary Clinton, the Democratic front-runner in 2016, and former President Bill Clinton have distanced themselves from the tough-on-crime laws implemented during the Clinton administration. Indeed, both Clintons wrote op-eds last month on the topic, which has gained national attention amid racially charged protests over police brutality and law enforcement tactics.

In his op-ed, Clinton described the anti-crime measures of the 1990s as an honest reaction to a very real and violent threat. However, he suggested that some of those policies may have overshot the mark and placed too much emphasis on incarceration.

For her part, Hillary Clinton has made criminal justice reform one of the most substantive planks of her nascent campaign. She gave a major speech on the issue last month, where she passionately lambasted the racial inequities present in the justice system.

"There is something profoundly wrong when African-American men are still far more likely to be stopped and searched by police, charged with crimes, and sentenced to longer prison terms than are meted out to their white counterparts. There is something wrong when a third of all black men face the prospect of prison during their lifetimes," Clinton said then. "We have allowed our criminal justice system to get out of balance and these recent tragedies should galvanize us to come together as a nation to find our balance again."

But Paul has also made criminal justice reform a key part of his candidacy. And he has repeatedly argued that his efforts reaching out to minority communities on the issue would make him a stronger general election nominee against Clinton than his GOP rivals.

On Monday, Paul also claimed partial credit for Clinton "changing her tune" and touted other policies he would implement to help urban neighborhoods.

"She's changing her tune because people like me have been speaking out against these injustices. I'll also ask her what she's going to do for poor people in Philadelphia. I have a specific plan that would dramatically lower the taxes for people who live in zip codes of poverty and high unemployment," he declared.

View Paul's remarks below, via NBC: