Medical cannabis has been touted as a solution to the US opioid overdose crisis since Bachhuber et al. [M. A. Bachhuber, B. Saloner, C. O. Cunningham, C. L. Barry, JAMA Intern. Med. 174, 1668-1673] found that from 1999 to 2010 states with medical cannabis laws experienced slower increases in opioid analgesic overdose mortality. That research received substantial attention in the scientific literature and popular press and served as a talking point for the cannabis industry and its advocates, despite caveats from the authors and others to exercise caution when using ecological correlations to draw causal, individual-level conclusions. In this study, we used the same methods to extend Bachhuber et al.'s analysis through 2017. Not only did findings from the original analysis not hold over the longer period, but the association between state medical cannabis laws and opioid overdose mortality reversed direction from −21% to +23% and remained positive after accounting for recreational cannabis laws. We also uncovered no evidence that either broader (recreational) or more restrictive (low-tetrahydrocannabinol) cannabis laws were associated with changes in opioid overdose mortality. We find it unlikely that medical cannabis-used by about 2.5% of the US population-has exerted large conflicting effects on opioid overdose mortality. A more plausible interpretation is that this association is spurious. Moreover, if such relationships do exist, they cannot be rigorously discerned with aggregate data. Research into therapeutic potential of cannabis should continue, but the claim that enacting medical cannabis laws will reduce opioid overdose death should be met with skepticism. medical cannabis | opioid overdose | public policy This article contains supporting information online at www.pnas.org/lookup/suppl/

Through their power to sentence, trial judges exercise enormous authority in the criminal justice system. In 39 American states, these judges stand periodically for reelection. Do elections degrade their impartiality? We develop a dynamic theory of sentencing and electoral control. Judges discount the future value of retaining office relative to implementing preferred sentences. Voters are largely uninformed about judicial behavior, so even the outcome of a single publicized case can be decisive in their evaluations. Further, voters are more likely to perceive instances of underpunishment than overpunishment. Our theory predicts that elected judges will consequently become more punitive as standing for reelection approaches. Using sentencing data from 22,095 Pennsylvania criminal cases in the 1990s, we find strong evidence for this effect. Additional tests confirm the validity of our theory over alternatives. For the cases we examine, we attribute at least 1,818 to 2,705 years of incarceration to the electoral dynamic.

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R egulatory agencies impose costs and benefits tailored to individual firms through their discretionary enforcement activities. We propose that corporations use political expenditures in part to "flex their muscles" to regulators and convey their willingness to fight an agency's specific determinations in the political arena. Because the signaling function of political expenditures is strategically complex, we derive a formal model wherein we demonstrate the existence of an equilibrium in which (1) large political donors are less compliant than smaller ones, but the bureaucracy monitors them less, and (2) firms with publicly observable problems reduce their political expenditures. We test the empirical implications of the model using plant-level data from the Nuclear Regulatory Commission on the inspection of 63 privately operated nuclear power plants and the political expenditures of their parent companies. We find strong evidence for the first prediction and qualified support for the second.

We propose a strategy to distinguish investment and consumption motives for political contributions by examining the behavior of individual corporate executives. If executives expect contributions to yield policies beneficial to company interests, those whose compensation varies directly with corporate earnings should contribute more than those whose compensation comes largely from salary alone. We find a robust relationship between giving and the sensitivity of pay to company performance and show that the intensity of this relationship varies across groups of executives in ways that are consistent with instrumental giving but not with alternative, taste-based, accounts. Together with earlier findings, our results suggest that contributions are often best understood as purchases of "good will" whose returns, while positive in expectation, are contingent and rare.