Remission or mitigation of forfeitures shall be governed by the applicable customs laws. (Sec. 613, 618, 46 Stat. 756, as amended, 757, as amended, sec. 4, 53 Stat. 1292, sec. 7327, 68A Stat. 871; 19 U.S.C. 1613, 1618, 49 U.S.C. 784, 26 U.S.C. 7327)