The 2020 Democratic campaign is already shaping up to be a battle of big ideas. From the Green New Deal to Medicare for All to a wealth tax, the candidates and the country are discussing bold responses to some of the greatest challenges of our times.

But when it comes to reforming our criminal legal system, the conversation hasn’t been as visionary — in fact, it’s been almost exclusively backward looking. Senators Kamala Harris and Amy Klobuchar are fending off criticism for actions they took as prosecutors. Should former Vice President Joe Biden enter the race, he can count on having to explain his role in championing regressive crime legislation in the 1980s and ’90s.

This scrutiny is entirely appropriate. Walk into any criminal courthouse, and you will find it packed with judges and prosecutors lecturing defendants on the importance of accepting responsibility for their choices. Come election time, the officials who built that system must accept responsibility for theirs.

But we should do more than look back. In a country that locks up more of its citizens than any other, we should demand that candidates for president have a plan for how they will confront mass incarceration and repair the harms it has caused. While most of the action in our criminal system takes place at the state and local level — almost 90 percent of prisoners are incarcerated in state, county, or local prisons or jails — the federal government still has an important role to play.