are typically too low. Subsequently, the seminal work of Katz and Shapiro (1986) has been extended in several directions. For example, Bhattacharya, Glazer, and Sappington (1992) have taken into account that the firms acquiring licenses must make further investments in order to develop marketable products. Schmitz (2002, 2007) has shown that asymmetric information due to adverse selection or moral hazard may lead the research lab to sell more licenses than it would do under complete information. Antelo and Sampayo (2017) have studied the optimal number of licenses in a signalling model. Criticism The provision of licenses and the agencies that mandate them are often criticised by American libertarians like Milton Friedman for creating an anticompetitive environment for occupations, which creates a barrier to entry for more qualified and skilled individuals who may not have the resources to obtain the necessary licences. According to Friedman, licenses and permits have become so burdensome due to legislation that favors the current establishment of wealthy occupants that they decrease the supply of such occupations, which raises prices for the average consumer. Libertarians and the anti-authoritarian left (anarcho-communists) view competing guilds and other voluntary communes as being more beneficial for disseminating the skills and education required to perform a specified career. See also References External links Business law Strategic alliances Revenue models