Thread by @AaronChalfin

Do police make late shift arrests in order to take advantage of overtime pay? This story is a mainstay of public criticism of law enforcement and reflects broader concerns about the distortionary effects of financial incentives in the US criminal justice system. But is it true?

At first blush, it might make sense that officers would want to make arrests at the end of the workday -- overtime pay is fixed 150% of an officer's base pay. As such the "price" of late shift arrests is higher. However, officers also face a labor-leisure tradeoff.

Exploiting the staggered timing of shift assignments
throughout the day in Dallas, TX, we find that officers, in fact, *reduce* their arrests (by 28%) at the end of their work shift. This result isn't an artifact of being routed to fewer service calls late in the shift.

The result is also very unlikely to be driven by the practice of "arrest trading" between officers, the incapacitative effect of making arrests earlier in the shift or by inaccurate time stamps on arrest data.

Officers are not more likely to make "low-level" arrests at the end of the day nor are late shift arrests more likely to involve Black or Hispanic suspects. Even among officers who are especially likely to make more late-shift arrests, the above propositions are true.

Moreover, the "quality" of arrests made, as measured through court convictions (for misdemeanors or felonies) and sentencing, tends to rise at the end of the workday.

While convictions and sentencing aren't perfect proxies for quality, the evidence does not suggest that late shift arrests are weaker or less likely to "hold up" than other arrests.

Why don't officers engage in "collars for dollars?" We don't think it's due to fatigue but it is, in part, due to the fact that they sometimes work off-duty jobs after work. On days in which officers 'moonlight' after a shift, they are 10% less likely to make late-shift arrests.

We estimate a dynamic model that rationalizes these findings. Given the value that officers place on avoiding false arrests and arresting guilty suspects, incentives created by overtime pay are insufficiently large to change police decision-making at the margin.

What about an officer's desire to obtain overtime for testimony in court? In Dallas this is, in fact, < 5% of overtime pay awarded to officers. Our research design which compares late to early shift arrests nets out this motivation.

Naturally, these findings are based on data from a single city. While we are unaware of any policy or practice that sets the Dallas PD apart from most other large police depts in this context, further replication is always always important!

The full paper (with Felipe Goncalves @UCLAEconomics ) is here: tinyurl.com/y4vqqk8l
Great reading on this and related topics: Cop in the Hood by @PeterMoskos and Arrest Decisions: What Works for the Officer? by Edith Linn.