Section 201 safeguard measures, also referred to as 'escape clause' measures, were developed to facilitate efforts by the domestic industry to make a positive adjustment to import competition. This positive adjustment to imports could involve industry restructuring to become more internationally competitive, or it could involve some domestic firms deciding to leave the market and focus on other lines of business. In the United States, the measures were born out of an understanding that trade liberalization could be highly disruptive to vulnerable domestic industries. A decision was made that a period of import relief should be available to such industries to adapt to new conditions of competition brought on by new trade concessions. Although this is in apparent contradiction to the purpose of trade liberalization and the efficient reallocation of resources, escape clause or safeguard measures were viewed by many as a necessary political safety valve, in the absence of which a consensus on trade liberalization in the United States could not be achieved.

Section 201 dates back to the Trade Act of 1974, but similar mechanisms have existed since the 1930s and the first statutory procedure and criteria for escape clause or safeguard actions appeared in the Trade Agreement Extension Act of 1951. Although the legislation has been amended a number of times since, the basic tenets are essentially still the same: following an investigation and determination by the United States International Trade Commission (previously the Tariff Commission), the President may impose duties or other restrictions for a limited period of time on increased imports of any article found by the Commission to cause or threaten to cause serious injury to the domestic industry producing the like or directly competitive article.

Source: Business Guide to Trade Remedies in the United States: Anti-dumping, countervailing and safeguards legislation practices and procedures