given that canada used to impose a standard royalty of per cent of the net selling price of the drug in final dosage form on a licensee of right to use patented pharmaceuticals until and given that most data originators will recoup the bulk of their rd expenses in developed countries anyway a royalty comprising the generic producer s own marginal costs of production plus per cent of these costs depending upon gdp per capita ability to pay would seem more than sufficient while such an approach would give only an approximation of the real costs of the originator s rd it would avoid the transaction costs and possibly endless litigation that more complicated models might induce finally it would also be limited in time for instance to five years during which the data originator would be entitled to claim compensation