The activity's objective has been to promote information exchange and co-operation between national programmes related to streaming of waste with particular regard to the implications of these strategies on recovery of energy from Municipal Solid Waste. All the countries participating in the IEA Separation Activity have source separation schemes for collecting recyclable materials, particularly paper and glass, from households. Production of a coarse or shredded RDF appears to be the best option for maximising the amount of energy recovered to the fuel product. Combinations between source separation, central hand-picking and other techniques makes it possible to sort out paper, glass, wood, metals, and plastics by colour and type etc. Fibres from material recovery of paper/carton, recycled one or a few times will eventually break down and come out of the process as waste where combustion or biological handling/composting is the natural choice of treatment. A legal decision by the United States Supreme Court has reversed a lower court's earlier decision upholding the practice of flow control. Flow control is the practice by a governmental entity, such as a municipality or county, requiring that waste within the jurisdiction of the entity be taken only to specified locations, even if the haulier is a private enterprise.