Professional Motivations in the Public Sector: Evidence from Police Officers

This paper studies how public sector workers balance professional motivations against private economic concerns, using arrest decisions by Dallas Police Department (DPD) officers as the empirical laboratory. The central institutional feature exploited is that arrests made near the end of an officer’s shift typically require the officer to stay and work overtime, generating private costs that must be weighed against the professional benefits of making an arrest (e.g., crime reduction or duty fulfillment). The paper further leverages variation from DPD’s “secondary employment” program: approximately 30% of officers held a registered second job at some point during 2019–2021, and on days when a second job is scheduled after the police shift, the opportunity cost of late-shift policing is higher.

The data cover all DPD arrests from January 2015 to December 2021, linked to officer shift assignments, charge types, prosecutorial outcomes (whether the Dallas County Attorney chose to prosecute), and second-job schedules. The sample excludes traffic violations and arrests without shift information. The authors observe wide variation in prosecution rates by charge type: drug and gang offenses exceed 70%, property and violent crimes run 30–50%, and minor charges fall below 20%.

Four main findings emerge. First, arrest rates fall sharply in the last 30–40 minutes of a shift, with the decline most pronounced for drug and gang charges (approximately 50% drop in arrest rate) and smallest for violent charges, consistent with officers having more discretion over the former. Second, arrests that do occur late in the shift are of higher quality: conditional on being made, they are approximately 1.5–2.5 percentage points more likely to result in prosecution than arrests made earlier, with the quality premium larger in more discretionary charge categories (drugs/gang > property > violent). Third, on days when an officer has a second job scheduled, arrest rates are lower by roughly 5–10% relative to baseline across the full shift, with effects concentrated in the second half; and the conditional probability of prosecution on those days is 1–2 percentage points higher than on non-second-job days. The second-job effect appears even earlier in the shift than the overtime effect alone, consistent with the second job magnifying the opportunity cost mechanism.

Fourth, the authors estimate a dynamic structural model of the arrest decision. At each moment of the shift the officer chooses whether to arrest, trading off a professional benefit b_p against a private cost c(t, secondjob) that rises when overtime begins and rises further on second-job days. Structural estimates indicate the overtime cost is large enough to reduce the expected professional value of an arrest in the final 30 minutes of the shift by roughly 20–30%. The additional second-job cost reduces expected professional value by a further 10–20%. Counterfactual simulation implies that eliminating the overtime cost would increase overall arrests by approximately 5–8%, a magnitude the authors describe as economically significant. Welfare analysis shows that the desirability of high overtime costs depends on whether citizens weight quantity of arrests or quality: under quality-weighted preferences the current overtime-cost regime may be socially optimal because officers self-select toward arrests they perceive as likely to result in prosecution; under quantity preferences, reducing overtime costs would increase police activity.

The identification strategy relies on within-officer variation in second-job scheduling, absorbing officer fixed effects (and officer-by-month fixed effects in robustness checks) and time fixed effects. The key identifying assumption is that second-job days are not systematically assigned to low-crime or low-patrol days. Supporting evidence includes balance tests showing second-job status is uncorrelated with local crime call patterns conditional on fixed effects, and the observation that officers who take second jobs do not exhibit a systematically different enforcement style (measured by arrest patterns across the shift) relative to officers who do not.

Scope conditions: results are from a single medium-sized urban police department (approximately 3,000 officers) in Dallas, Texas, a city described as diverse by race, income, and political affiliation. The department is 29% Black, 43% Hispanic, 27% White, and 15% female. Generalizability to other jurisdictions or institutional structures is not established by this study.

Q: What is the main research question? A: The paper asks how public sector workers balance professional motivations (e.g., crime reduction, duty fulfillment) against private economic concerns (e.g., overtime costs, opportunity costs from second jobs). It uses police arrest decisions as the empirical setting because the shift-end timing of arrests generates a clear, observable private cost that varies within officer across days.

Q: What is the key institutional feature that generates identification? A: Arrests made near the end of a shift typically require the arresting officer to stay past the shift and work overtime. This creates a personal cost — more time, delayed transition to off-duty activities — that makes late-shift arrests more costly without changing their professional value. The DPD secondary employment program adds a second source of variation: on days when an officer has a registered second job scheduled after the police shift, the opportunity cost of any arrest (and especially a late-shift arrest) is higher.

Q: How large is the drop in arrest rates near shift end? A: The baseline arrest rate declines by approximately 0.12 percentage points per six-minute time bucket in the last 30 minutes of the shift, or about 5% relative to the mean arrest rate of 2.3 percentage points. The drop is most dramatic for drug and gang charges, where the arrest rate falls by approximately 50%, and smallest for violent charges, where officers appear to arrest regardless of shift timing.

Q: How does arrest quality change near shift end? A: Arrests made in the last 30 minutes of a shift are approximately 1.5–2.5 percentage points more likely to result in prosecution than arrests made earlier in the shift, after controlling for charge type composition and officer fixed effects. The quality premium is larger in more discretionary charge categories (drugs/gang, then property, then violent), consistent with officers becoming more selective to avoid overtime costs on arrests unlikely to result in prosecution.

Q: Does the shift-end drop reflect officer fatigue or overtime cost? A: The paper argues both pieces of evidence point to overtime cost rather than fatigue alone. First, arrest rates increase sharply after the official shift end when the officer is already earning overtime pay — if fatigue were the mechanism, arrests would also decline post-shift. Second, on second-job days arrest rates fall earlier in the shift and by more, consistent with higher opportunity costs rather than accumulated fatigue.

Q: What is the effect of having a second job scheduled on arrest rates? A: Having a second job scheduled reduces arrest rates by roughly 5–10% relative to the baseline across the full shift, with effects concentrated in the second half. The reduction is even larger in the final 30 minutes, consistent with the second job amplifying the overtime cost mechanism.

Q: What is the effect of second-job days on arrest quality? A: Arrests made on second-job days are 1–2 percentage points more likely to result in prosecution compared to arrests on non-second-job days, after controlling for time of day, charge type composition, and officer fixed effects. This parallels the shift-end quality effect and is consistent with officers applying higher selectivity thresholds when opportunity costs are elevated.

Q: How is the second-job variation used for identification? A: The main specification compares the same officer’s behavior on shifts where a second job is scheduled versus shifts where it is not, absorbing officer fixed effects and time fixed effects. The identifying assumption is that second-job scheduling is uncorrelated with unobservable determinants of enforcement intensity conditional on fixed effects. The authors support this with balance tests showing second-job status is not predicted by lagged activity measures or contemporaneous crime call patterns.

Q: What does the dynamic structural model add? A: The structural model formalizes the arrest decision as a dynamic problem where the officer compares the professional benefit b_p of an arrest to the private cost c(t, secondjob), which rises discontinuously when overtime begins and rises further on second-job days. Estimating the model by matching moments (baseline arrest rates, shift-timing patterns, quality changes, second-job effects) yields preference parameters. The model enables counterfactual and welfare analysis that the reduced-form estimates alone cannot provide.

Q: What are the structural estimates of overtime and second-job costs? A: The overtime cost c_ot is estimated to be large enough that arresting someone in the final 30 minutes of the shift reduces the expected professional value of that arrest by roughly 20–30%. The additional second-job cost c_sj reduces expected professional value by a further 10–20%. Both estimates are described as statistically precise.

Q: What does the counterfactual removal of overtime costs imply for arrests? A: Eliminating the overtime cost is estimated to increase overall arrests by approximately 5–8%, which the authors characterize as economically significant. This implies that officers’ private costs have a first-order impact on the quantity of law enforcement activity.

Q: What does the welfare analysis conclude about overtime costs? A: The welfare effect of eliminating overtime costs depends on citizen preferences. Under quality-weighted preferences — where citizens value the probability that an arrest results in prosecution — the current overtime-cost regime may be socially optimal because it induces officers to self-select toward arrests they perceive as likely to stick. Under quantity preferences — where citizens value the total number of arrests per period — reducing overtime costs would increase police activity and benefit citizens.

Q: What are the scope conditions of the study? A: The study is conducted entirely within the Dallas Police Department, a single medium-sized urban department with approximately 3,000 officers. Dallas is described as a diverse city by race, income, and political affiliation, and the department itself is relatively diverse (29% Black, 43% Hispanic, 27% White, 15% female). The findings may not generalize to departments with different overtime rules, labor contracts, or institutional cultures.

professional motivations: The non-pecuniary benefits officers derive from making arrests, such as crime reduction, duty fulfillment, or the legitimacy of their work; modeled as a professional benefit b_p that motivates arrest independent of financial compensation.

private costs of arrest: The personal costs borne by officers when making an arrest, chiefly the overtime cost when an arrest extends the shift past its scheduled end, and the opportunity cost on days when a second job is scheduled. These costs are distinct from professional motivations and respond to economic incentives.

arrest quality: The conditional probability that an arrest results in prosecution by the Dallas County Attorney’s office; used as a revealed-preference measure of the officer’s assessment of arrest strength. Higher arrest quality near shift end reflects greater selectivity under elevated private costs.

secondary employment (second job): A formal DPD program allowing officers to register as certified police officers for private security work after their primary shift. Approximately 30% of DPD officers held a second job at some point during 2019–2021. The scheduled second job raises the opportunity cost of late-shift primary-shift arrests and provides a second source of variation in private costs.

overtime cost: The cost incurred when an arrest requires an officer to remain past the end of the scheduled shift to complete paperwork and processing. Modeled as c_ot per period spent in overtime, this cost is the primary mechanism reducing late-shift arrest rates and increasing arrest selectivity.

dynamic model of arrest decisions: A structural model in which officers decide each moment whether to arrest, balancing professional benefit against private cost as a function of shift timing and second-job status. Estimated by minimum distance on moments from the data; used to recover preference parameters and conduct counterfactual welfare analysis.