Tariff
In contrast, in economic theory tariffs are viewed as a primary element in international trade with the function of the tariff being to influence the flow of trade by lowering or raising the price of targeted goods to create what amounts to an artificial competitive advantage. When tariffs are viewed and used in this fashion, they are addressing the country's and the competitors' respective economic healths in terms of maximizing or minimizing revenue flow rather than in terms of the ability to generate and maintain a competitive advantage which is the source of the revenue. As a result, the impact of the tariffs on the economic health of the country are at best minimal but often are counter-productive.
Reciprocal Tariff Act
Before the RTAA, if Congress wanted to establish a lower tariff for particular imports, it would act unilaterally, taking the foreign country's tariff rate as fixed. Congress would choose a tariff rate that was either a little higher or lower than the median preferred tariff, depending upon the composition of the Congress. Generally, a Republican controlled Congress would prefer higher tariffs and a Democrat controlled Congress would prefer lower tariffs. Thus, tariffs were chosen based on the domestic politics of the United States. Individual members of Congress were under great pressure from industry lobbyists to raise tariffs to protect them from the negative effects of foreign imports. 
The RTAA’s novel approach freed Roosevelt and Congress to break this trend of tariff increases. First, it tied tariff reductions by the United States to reciprocal tariff reductions with international partners. It also allowed Congress to approve the tariffs with a simple majority, as opposed to the requisite two-thirds majority necessary for other treaties. Lastly, the president had the authority to negotiate the terms. These three innovations in trade policy created the political will and feasibility to enact a more liberal American trade policy. 
Reciprocity was an important tenet of the trade agreements brokered under RTAA because it gave Congress more of an incentive to lower tariffs. As more foreign countries entered into bilateral tariff reduction deals with the United States, American exporters had more incentive to lobby Congress for even lower tariffs across many industries. 
By giving the President the authority to negotiate these deals, the Congress effectively ceded a part of their power (authorized under US Constitution, Article I, Section VIII) to the executive branch. The President had to consider the aggregate welfare of all Americans, his foreign policy priorities, and what was feasible with other countries in making his decisions on tariffs. These considerations generally left presidents more inclined to reduce tariffs than the Congress. Whether Roosevelt or Congress foresaw this result is a matter of historical debate.