Do laws protecting tenants' health work?: Implied warranties of habitability and respiratory health.

Housing quality is a powerful determinant of health. When US renters' housing conditions deteriorate, state policies known as "implied warranties of habitability" are meant to force landlords to ameliorate pathogenic habitability violations, allowing renters to sue or withhold rent until repairs are completed. No research, however, has tested whether these policies work-whether they succeed at protecting population health. At issue is whether warranties are effective when bringing legal action is so onerous for renters in practice. We thus use generalized difference-in-differences models to estimate warranties' effects on renters' general and respiratory health, including event study and triple-difference models that employ homeowners as negative controls. Health outcome data from the National Health Interview Survey (1993-2018) was limited to the 10 states that did not have a warranty at baseline and had sufficient pre-implementation data. We found null associations near 0 for nearly all outcomes. It is unclear whether this is because (A) our sample mostly included states with weak policies, (B) US renters are not guaranteed lawyers in civil court, or (C) a completely different, more pro-active rental inspection approach is needed. Regardless, results suggest policies must change if we are to realize the public health promise of healthier housing.