Numerous examples may be quoted of policies being both advocated and condemned on health grounds. Policies that increased wealth inequality have been defended on the grounds that all would benefit through ‘trickle down’, but more recent work has demonstrated that increasing inequality was more likely to damage health (Wilkinson, 1996). Economic adjustment policies may have beneficial effects of increasing macroeconomic stability and growth, and encouraging better use of natural resources through pricing policies. These benefits have to be set against the harm of adverse effects on income distribution of vulnerable groups, resulting from greater reliance on market mechanisms (Warford, 1995). Policies to discourage smoking were initially opposed on the grounds that they would reduce exchequer income and thereby the ability to provide health and welfare services (Pollock, 1999). Reducing tobacco sales has been opposed on the grounds that it would increase unemployment but Godfrey et al. demonstrated that redirecting expenditure from tobacco to other goods was likely to increase employment (Godfrey et al., 1995). Health Impact Assessment claims to assist policy making by identifying the different paths through which health may be benefited or harmed, and by estimating the balance of harm and benefit. By assessing the relative importance of impacts through different routes it provides information to help the trade-offs which are inherent in all policy making.