Strategies of Research Design in the Legal Impact Study: The Control of Plausible Rival Hypotheses

A legal impact study represents an attempt to ascertain how a particular law affects the conduct and attitudes of those individuals, groups or other relevant units located in jurisdictions where that law is in force. By its very nature such a study involves one essential comparison; the comparison between actual behavior patterns in jurisdictions having the law in question and the behavior patterns which would have existed in those same jurisdictions had the law in question never been enacted. Since this comparison is one which by definition cannot actually be made, the problem for the legal impact theorist is how to estimate best what the behavior patterns would have been in a certain jurisdiction had the law in question never existed there. The legislator or court seeking to determine the actual or probable effects of a law faces a similar problem.