Washington (CNN) Former Vice President Joe Biden said in remarks at a Martin Luther King Jr. breakfast Monday that he has made mistakes when it comes to criminal justice issues, an area of his career that could be scrutinized if he launches a 2020 presidential bid in a competitive Democratic field.

"You know I've been in this fight for a long time. It goes not just to voting rights. It goes to the criminal justice system," Biden said at the National Action Network's Martin Luther King Jr. breakfast in Washington. "I haven't always been right. I know we haven't always gotten things right, but I've always tried."

Biden made no mention of his support for a 1994 crime bill that set strict sentencing standards and, critics have argued, led to an era of mass incarceration. But he highlighted his later work with President Barack Obama to address the sentencing disparity for crack versus powder cocaine.

"It was a big mistake when it was made," he said. "We thought, we were told by the experts, that crack you never go back, it was somehow fundamentally different. It's not different. But it's trapped an entire generation."

The former vice president also argued that white Americans must acknowledge systemic racism still exists.

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