Next to be considered are controls designed to forestall interruption of vital production. Section 8 of the War Labor Disputes Act required 30 days notice of a prospective strike and secret balloting of the union members concerned.[369] Other sections of the Act authorized government seizure of struck plants, and made it unlawful to interfere with government operation of plants.[370] The Labor Management Relations Act of 1947 set forth procedure whereby the President may secure injunctions postponing strikes or lockouts which will, if permitted to occur or to continue, imperil the national health or safety.[371] _Controlling Profits_: The campaign of the 1930’s to take the profits out of war is well known. Correlative to the deeply felt aspiration in time of peace to end the resort to war as an instrument of policy, is the popular thesis that war and the profitability of war production have a causal connection. In time of war, the public, on the other hand, is receptive to the proposal that command of the services and lives of mature young human beings warrants conscription of capital at least to the extent necessary to avoid profiteering, or to the extent such conscription facilitates the attainment of other worthy defense goals. In harmony with these beliefs the Vinson-Trammell Act of 1934 authorizing naval construction within the limits of the Washington and London treaties of 1922 and 1930 instructed the Secretary of the Navy to make no contract for the construction and/or manufacture of any complete naval vessel or aircraft, or any portion thereof unless the contractor agreed to certain conditions: (1) he had to agree to pay any profit in excess of ten percent of the total contract price to the United States Treasury (twelve percent was allowed as the profit margin on aircraft); and (2) he could make no subdivisions of any contract or subcontract for the same article or articles for the purpose of evading the provisions of the Act.[372] In 1938 provisions for close supervision of the leasing of naval petroleum reserves also were imposed upon the Navy Department, obviously directed in part at precluding extortionate profit-making from such leases.[373]