Is assisted suicide a substitute for unassisted suicide?

Posner hypothesised that the legalisation of assisted suicide may substitute for unassisted (unregulated) suicide. We test predictions arising from this hypothesis using data from US states that have legalised assisted suicide. Event study regression estimates provide strong evidence that legalisation of assisted suicide is associated with an increase in total suicides, especially for females and older people. There is some evidence that assisted suicide laws are also associated with a smaller increase in unassisted suicide, though the statistical significance is weaker than for total suicides. Results using the synthetic control method (SCM) are generally consistent with the regression estimates. Overall the US experience to date provides little evidence in support of the Posner substitution hypothesis.