Proprietors must ensure that scales used to weigh packages are tested at least every 6 months and whenever they are adjusted or repaired. However, if a scale is not used during a 6-month period, it is only necessary to test the scale prior to its next use. Scales used to weigh packages that hold 10 wine gallons or less must indicate weight in ounces or hundredths of a pound.

(26 U.S.C. 5204)