tradeable permits approaches have had some success, such as the U.S.'s sulphur dioxide trading program or the EU Emissions Trading Scheme, and interest in its application is spreading to other environmental problems. Taxes and tariffs on pollution. Increasing the costs of polluting will discourage polluting, and will provide a "dynamic incentive", that is, the disincentive continues to operate even as pollution levels fall. A pollution tax that reduces pollution to the socially "optimal" level would be set at such a level that pollution occurs only if the benefits to society (for example, in form of greater production) exceeds the costs. This concept was introduced by Arthur Pigou, a British economist active in the late nineteenth through the mid-twentieth century. He showed that these externalities occur when markets fail, meaning they do not naturally produce the socially optimal amount of a good or service. He argued that “a tax on the production of paint would encourage the [polluting] factory to reduce production to the amount best for society as a whole.” These taxes are known amongst economists as Pigouvian Taxes, and they regularly implemented where negative externalities are present. Some advocate a major shift from taxation from income and sales taxes to tax on pollution - the so-called "green tax shift". Better defined property rights. The Coase Theorem states that assigning property rights will lead to an optimal solution, regardless of who receives them, if transaction costs are trivial and the number of parties negotiating is limited. For example, if people living near a factory had a right to clean air and water, or the factory had the right to pollute, then either the factory could pay those affected by the pollution or the people could pay the factory not to pollute. Or, citizens could take action themselves as they would if other property rights were violated. The US River Keepers Law of the 1880s was an early example, giving citizens downstream the right to end pollution upstream themselves if the government itself did not act (an early example of bioregional democracy). Many markets for "pollution rights" have been created in the late twentieth century—see emissions trading. According to the Coase Theorem, the involved parties will bargain with each other, which results in an efficient solution. However, modern economic theory has shown that the presence of asymmetric information may lead to inefficient bargaining outcomes. Specifically, Rob (1989) has shown that pollution