From the Summary: "Importers often request that Members of Congress introduce bills seeking to suspend or reduce tariffs on certain imports on their behalf. The vast majority of these commodities are chemicals, raw materials, or other components used as inputs in the manufacturing process. The rationale for these requests, in general, is that they help domestic producers of the downstream goods reduce costs, thus making their products more competitive. In turn, these cost reductions can be passed on to the consumer. In recent congressional practice, the House Ways and Means and Senate Finance Committees, the committees of jurisdiction over tariffs, have combined individual duty suspension bills and other technical trade provisions into larger pieces of legislation known as miscellaneous tariff bills (MTBs). Before inclusion in an MTB, the individual legislative proposals introduced by Members are reviewed by the trade subcommittee staff in each committee, the U.S. International Trade Commission (USITC), and several executive branch agencies to ensure that they are noncontroversial (generally, that no domestic producer objects) and relatively revenue-neutral (revenue loss of no more than $500,000 per item). […] This report, first, briefly presents a discussion of the MTB legislation debated in the past few Congresses. Second, the reviews of individual duty suspension bills by House Ways and Means and Senate Finance committee staff, the U.S. International Trade Commission (USITC), and other relevant agencies are discussed. Third, the report presents some pros and cons for MTB passage. Fourth, 'Table 1' at the end of the report illustrates MTB legislation considered in Congress from the 97th Congress (1983) to the present."
CRS Report for Congress, RL33867