On this day in 1947, the Labor Management Relations Act of 1947 (better known as the Taft-Hartley Act) garnered six more votes than necessary to override President Truman's veto and become law, one that is still in effect today.
The post-World War II economy had experienced a huge labor upsurge, and with that an increase in labor union participation. Additionally, unions had taken a no-strike pledge during the war, and their built-up resentments exploded at war's end.
In general, President Truman was not happy with the havoc the numerous strikes wreaked on the post-war economy. In the United Mine Workers strike in the Spring of 1946, he threatened to use the army as strikebreakers and take government control of railroads. An agreement was made (on the President's terms) before he had to make good on his threats.
Nonetheless, the Democrat believed firmly in the rights of labor unions, in part because they kept government out of enterprise. In his veto (excerpted below) he argued that by restricting unions, the bill imposed too much government into private economic affairs, and disrupted the balance of power between labor and management.
"Our basic national policy has always been to establish by law standards of fair dealing and then to leave the working of the economic system to the free choice of individuals. Under that policy of economic freedom we have built our nation's productive strength. Our people have deep faith in industrial self-government with freedom of contract and free collective bargaining...
This [bill] is a long step toward the settlement of economic issues by government dictation. It is an indication that industrial relations are to be determined in the halls of Congress, and that political power is to supplant economic power as the critical factor in labor relations."
President Truman's full Veto
NYT Article after the Taft-Hartley bill passed