Although identification and analyses of non-tariff measures (NTMs) has significantly evolved, understanding their nature, extent and trade effects remains a challenge for analysts and policymakers. OECD has engaged in a systematic review of available information on non-tariff barriers to trade and an examination of particular types of measures, drawing attention also to how procedural aspects themselves can pose additional impediments to the free flow of trade and investment - how border and behind-the-border policies are designed, applied or enforced.

Why and how are particular measures used? What are their economic effects for importing and exporting countries? OECD research carried out in such areas as non-automatic import licensing, export duties and other export restrictions has provided some answers and background information underpinning the discussions on non-tariff barriers to market access on the Doha Development Agenda.

Concerns voiced by the private sector and disputes between governments indicate the persistent importance of this broad category of measures. Technical barriers to trade (TBT) and other domestic policies in importing countries make market access difficult, while they may serve legitimate goals unrelated to trade. Non-tariff barriers of particular concern to developing countries have also been considered. More recently, analysis has focused on conformity assessment procedures from a market-access perspective.

Another strand of this work has taken stock of different methods for empirically measuring the trade costs of a broad range of NTMs. The effects of customs procedures and delays on trade flows have been quantified and efforts are currently under way to analyse transport costs so as to better understand the role that these costs play in traders’ overall transaction costs.