customs
Explicit limits, or quotas, on the physical amounts of particular commodities that can be imported or exported during a specified time period, usually measured by volume but sometimes by value. The quota may be applied on a “selective” basis, with varying limits set according to the country of origin, or on a quantitative global basis that only specifies the total limit and thus tends to benefit more efficient suppliers. Quotas are frequently ministered through a system of licensing.
WTO
The World Trade Organization (WTO) generally prohibits the use of quantitative restrictions, except under conditions specified by other WTO articles.
See quotas; General Agreement on Tariffs and Trade (GATT), World Trade Organization (WTO).