Rule on investor-state dispute settlement (ISDS) offer investors the possibility to sue their host states for alleged breaches of an investment agreement. Are such rules in the Transatlantic Trade and Investment Partnership (TTIP) agreement necessary? What risks are there for environmental regulation? Will states have to pay compensation for environmental protection measures? The Ecologic Institute analyzed the potential influence of ISDS rules in TTIP on environmental regulation. The resulting study is available online.