The members do. Every level of the IAM operates on the democratic principle of majority rule. IAM members have the right to participate in local lodge meetings, vote for local and international officers and vote on contracts and convention delegates. The Grand Lodge Convention, which convenes every four years, is the highest governing body in the union. Elected delegates set union policy and have the power to amend the IAM Constitution.
All members belong to a local lodge which has jurisdiction in their city, town, or area.
Every local must hold at least one monthly meeting for members to vote on expenditure of union funds, conduct local business, and discuss member concerns. Most locals are organized into districts covering a particular type of industry. All locals and districts come under the jurisdiction of the International, or Grand Lodge. The International maintains a headquarters near Washington, D.C. to administer the union and to implement programs and policies mandated by the Grand Lodge Convention. The Transportation Department has its office at headquarters and oversees agreements in the airline, railroad, automotive and trucking industries.