Torts folks might be interested in a recent paper by Griffin Sims Edwards (Emory, Econ), Doing Their Duty: An Empirical Analysis of the Unintended Effect of Tarasoff v Regents on Homicidal Activity. In it, the author seeks to "tease out the dominating effect of Tarasoff by using a codification of Tarasoff laws and a fixed effects (FE) model to estimate Tarasoff’s effect on homicides in the United States." The abstract follows:
"The effect of state duty to warn laws inspired by Tarasoff v. Regents has been debated for decades. Required reporting of patient threats to the authorities and potential victims gives incentive to the mental health professional to not meet with the most at risk patients, or at very least make the current state of the law abundantly clear to the patient as to suggest suppression of the most at risk statements leaving the psychologist in liability-free ignorance to the true mental state of the patient. As a result, the mental help needed to treat the patient may be foregone and violence may ensue. Exploiting the variation in the timing and style of duty to warn laws across states, I use a fixed effects model to find that, all else equal and controlling for the prevalence of crack, mandatory duty to warn laws cause an increase in homicides of 9.5% or 0.83 people per 100,000. These results are robust to model specifications, falsification tests, and help to clarify the true, albeit unintended, affect of state duty to warn laws."