Case Study: How Yolo County Used Data to Identify and Address DUI Disparities

Situation

The Yolo County District Attorney’s Office in California has made data-informed decision-making a central part of its approach to criminal justice.

Since launching Commons with Measures for Justice in 2021, the office has used publicly accessible data to better understand how cases move through the justice system and to inform policy changes, including race-blind charging and expanded diversion opportunities.

For Deputy District Attorney Diane Ortiz, this work is particularly personal. As one of the few Latina prosecutors in California, Ortiz is deeply committed to ensuring that Latino communities feel protected and represented by the justice system.

That commitment became especially important when data revealed a troubling disparity in DUI arrests.

Problem

While reviewing Commons data, a relatively new attorney in the Yolo County District Attorney’s Office noticed that Latino defendants were being arrested for DUIs at significantly higher rates than white defendants.

In some months, nearly twice as many Latino people were being arrested for DUI.

The disparity raised an important question: Why?

DUI arrests can have significant consequences, including license suspension, lost employment opportunities, legal expenses, and other financial and personal impacts. At the same time, the office wanted to ensure that its response to the disparity did not compromise public safety.

The challenge was to understand what was driving the difference and identify ways to reduce DUI incidents and arrests across communities.

As Ortiz put it:

“We couldn’t unsee what we saw, so now it’s our responsibility as DAs to look into things.”

Without accessible, disaggregated data, the office may never have recognized the disparity or known where to begin investigating it.

Solution

The Yolo County District Attorney’s Office used Commons to identify the disparity and then launched a broader investigation into what might be contributing to the trend.

Ortiz spearheaded an effort that included outreach to:

  • Local law enforcement partners
  • Leaders in the Hispanic community
  • Community members and stakeholders

The office recognized that the data alone could not explain why the disparity existed. Instead, it provided the starting point for asking better questions and engaging the people closest to the issue.

Education became an important part of the response. Ortiz focused on helping community members understand:

  • The legal consequences of driving under the influence.
  • What constitutes the legal limit.
  • The risks associated with impaired driving.
  • Steps people can take to avoid driving under the influence.

The approach combined data analysis with community engagement, using data to identify a potential problem and relationships to better understand and address it.

Results

The investigation is ongoing, and multiple factors may contribute to the disparity. However, the data following Ortiz’s outreach showed encouraging movement.

DUI Arrests Began to Decline

After peaking in 2023, DUI arrests among both Hispanic and white defendants began trending downward in the months following the outreach.

The Disparity Began to Narrow

The gap between Hispanic and white DUI arrests also began to close, suggesting that the combination of data-informed investigation and targeted community engagement may be contributing to improved outcomes.

Data Enabled Earlier Intervention

Perhaps most importantly, Commons allowed the District Attorney’s Office to identify a concerning trend that might otherwise have gone unnoticed.

Rather than simply reacting to individual cases, the office could see a broader pattern, investigate it, and take action.

Impact

The Yolo County experience demonstrates the power of pairing accessible public data with engaged leadership and community partnership.

Commons did not tell the District Attorney’s Office why the disparity existed or prescribe a solution. Instead, it made the pattern visible and gave leaders the information they needed to ask better questions and begin addressing the issue.

For Ortiz, that visibility was essential:

“But for Commons, I don’t know how we would have known any of this was happening.”

The result is a model for how data can support a more proactive approach to public safety: identify disparities, investigate their causes, engage the communities affected, and use what you learn to inform action.

Data doesn’t provide all the answers. But it can help justice leaders see the questions they need to ask and give communities a starting point for creating safer, more equitable outcomes.