An attempt to use disclosure laws passed by two US states to discover the sums of money paid by drug companies to doctors found the relevant information was of limited quality and hard to access.

The US states of California, Maine, West Virginia, Vermont, Minnesota, and the District of Columbia have laws mandating disclosure of payments made to doctors by drug companies. In two of these states, Vermont and Minnesota, payment disclosures are meant to be publicly available.

The Vermont law, enacted in 2001, requires drug companies to disclose any gift or payment of $25 (£13; €19) or more to doctors, hospitals, nursing …