Roughly half a million people are in jail despite not being convicted of anything. That's roughly 25% of the incarcerated population in the US. 1/4 people behind bars are (presumed) innocent right now, even if they may later be found guilty.

That's a problem. Being in jail for a few weeks or even a few days can totally fuck someone's life over, costing them a job, a relationship, their health, or worse.