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Behind David Whyman's State Preemption Evidence Dashboard

State preemption refers to the decision of a state to override the law of a lower authority (e.g. a city) when the two authorities conflict on policy measures. To avoid disparities in policy implementation, states use preemption to nullify pre-existing municipal ordinances or prevent a city from using its local authority to control specific policy measures. Regulations on ride-sharing, minimum smoking age, paid sick leave, minimum wage, and rent control are often preempted by states to ensure a statewide standard on each issue area. Preempting a policy is a major decision that necessitates a comprehensive overview of the evidence that evaluates the effectiveness and impacts of each policy. This task is daunting and oftentimes difficult for policymakers to undertake given the volume of inconclusive or contradictory research that exists on a particular policy.

To ease this process, PDI Alumni Advisor David Whyman collaborated with the Urban Institute to produce an interactive dashboard that shows the evidence on state preemption policies across 13 issue areas. The dashboard outlines the state of the evidence base among each issue area, allowing its users to visualize the amount, quality, and findings of the evidence behind various policy impacts. In reflecting on his work with the Urban Institute, the Paul Douglas Institute had a conversation with Whyman on the key elements, the creation, and the significance of his dashboard.


Tell us about this project that you worked on with the Urban Institute on state preemption. Could you give us a brief overview of state preemption?

It was the summer of 2018 and I was interning at the Urban Institute, and they were doing a project with the local solutions support center regarding state preemption and with the stage of the project, I was involved in conducting research on the evidence base on the effectiveness of state and local policies. We were reviewing the evidence on local policies because the idea is, if we can find that local policies that are the target of state preemption are effective, then that means there's a real cost to state preemption.

It would first be helpful to talk about what state preemption is. State preemption is when a state decides that the localities within it don't have the right to make policies on a certain issue, so for example, like one common area where there's preemption is rent control, so the state will establish a uniform policy across the state on rent controls, and the locality is not allowed to deviate from that policy. In this case, the rule is that the state has a ban on rent control, and localities aren't allowed to have their own rent control. It can also go in the other directions where some states have their own set standard for some policy, rather than a state mandate of the absence of that policy.

The idea is there are a lot of policies that are being targeted for state preemption across various issues from gun control, nutrition, housing. We did a big literature review of the evidence of the effectiveness of these local policies.

What was the motivation for the project?

The Urban Institute was bringing together different people from foundations around the country to coordinate a national strategy about state preemption. There was a convening at the local solutions support center held in Phoenix, Arizona in October 2018 where all the different researchers working on preemption projects presented their findings and had a discussion for ways to present this research to policymakers.

Why is it important that we have a collective view of the issues targeted in this project?

It's important to know the scope of the issues that state governments are targeting for preemption because it tells you which interest groups [the specific issue] is relevant to, and by informing these groups they might be mobilized to do something. This project in particular—finding evidence on the effectiveness of local policies—is that in a lot of ways, state policies go in one direction. With this project, we can evaluate the effectiveness of the direction that states go into with regard to certain policies. For example, there was one that showed how nutritional labeling, like menu labeling, is effective in reducing calorie consumption at restaurants.

How does the dashboard work?

The dashboard is visualizing the evidence base on each issue area. For each issue area, we found studies on the effectiveness of the laws on certain policies; that is, the ability of the law to achieve its intended goals. It categorizes the studies among a variety of different qualitative metrics based on the strength of the evidence, the type of the evidence, and whether or not it was for or against the effectiveness of the policy. What the dashboard allows you to do is visualize the balance of evidence for each issue area. It's not necessarily tied to any geography, but one thing the evidence dashboard shows is the number of states that have passed partial preemption laws for each issue.

What's your target audience when it comes to the use of this dashboard?

There's a number of levels to use this dashboard. One way is that it can inform the public about these various issues. Also, people who might not be specifically researching preemption but issues that are targeted by preemption, might come across this dashboard and realize that this is an issue that also intersects with preemption and will then decide to look more into the concept of preemption. The other thing is that as we were going around, there are some things called evidence banks, where they have a dashboard of each issue area, but most of the ones we were looking at weren't really evidence banks. So this could be a way for people who were looking for a non-partisan evaluation of the field of research that's been produced by scholars up to this point can determine whether or not the evidence base says policies rent control is effective. Even if you don't care about preemption, I think the dashboard is helpful.

This is a very meta, multi-faceted approach. What do you consider to be the main takeaway of the creation of the dashboard for future policymakers?

I would say, even setting aside preemption, I was surprised by the number of issue areas for which lacked a high volume of high-quality evidence. Like with ridesharing, people talk about it constantly, and yet there's little evidence on the effectiveness of ridesharing regulations. A lot of the research that's out there and the scholarship out there is just focused on analyzing aspects of the situation itself, or using case studies and qualitative analyses to express their views on the subject. But there's very little high-quality evidence on the actual effectiveness that's oriented towards policy. Which was surprising, because, for me, these seemed like such basic questions. It's like, "why would we consider implementing this policy? Is it going to work or not?" That's a pretty basic question, and I was so surprised there hadn't been more scholarship on these issues. On some of them, the jury was still out on whether or not the policy was effective at all. I think that could hopefully inspire more research in these areas.

So let's say next summer, some intern at the Urban Institute revisits this dashboard. What kind of actionable next steps would you like to see from someone who continues the work of this dashboard? What would you like to add to this project?

I don't know what the state of the project is currently right now, but something that would be interesting is to update some of the more recent issues like ridesharing to see if the evidence base has changed in the 2 years since I worked on this project. Other than that, it would depend on what the state of the project is with our client.


Whyman’s dashboard provides a comprehensive, innovative method of visualizing data on some of the most prominent policies that states choose to preempt. You can interact with the 13 different issue areas listed in the dashboard and access the in-depth literature review narratives for each area through the dashboard embedded on our website, or visit David’s website.

For those interested in a full view of Whyman’s methodology and a discussion of specific areas, a full transcript of the interview is available here.

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