The first post in this series addressed general principles for identifying and analyzing possible regulatory actions that either could have prevented Sandy Hook or prevent future such events. Subsequent posts discussed, in general terms, various regulatory options including changes in physical security at elementary schools, changes in personal security at elementary schools, and more stringent gun control.
Today we consider regulations that would change mental health screening and treatment — that is, regulating certain people rather than places (such as schools) or articles (such as guns). The reason this alternative may be appealing is that mass murders have been committed predominantly by persons with verified or suspected mental illness. It is plausible that some combination of improved diagnosis, screening for a predilection toward violence, and treatment could reduce the numbers of future mass murders.
The focus here is on a pragmatic question (would regulation be effective?) and a technical one (would regulation be efficient — i.e., less costly than other alternatives of equal effectiveness?). Debating legal and constitutional matters is left to others, but such debates should be irrelevant for any regulatory alternative that would not be effective. Regulations that are ineffective have no social benefits, and it is therefore impossible for them to ever be efficient.