AbstractDuring the UN Conference on Environment and Development (UNCED), many governments recognised the risks attached to the deliberate release of genetically-manipulated organisms (GMOs), but failed to discuss in any detail a liability regime for such releases. This is one of a number of factors that preclude confidence that large-scale environmental release of GMOs, which now seem inevitable, can be carried out safely. Safety policy could not begin to be effective without some internationally harmonised provision for strict and retrospective liability, and clean up, should a released GMO turn hazardous. An effective liability regime will be extremely difficult to achieve operationally: the precautionary and polluter-pays principles, it is argued, will be difficult-to-impossible to apply in their strictest definitions for GMO releases.