Beer keg registration is a legal requirement in some U.S. states and localities that identification tags or labels be affixed to beer kegs upon retail sale. They often consist of requirements that tags and records retained by the retailer list the name and address of the purchaser, the date and location where the beer will be served, and other information. These laws vary widely in their specifics and enforcement. There appears to have been little academic study of the efficacy of beer keg registration laws.
List of American states with beer keg registration Laws
- California - seven or more gallons
- District of Columbia 
- Iowa 
- Missouri 
- New Hampshire
- New Mexico
- New York - four or more gallons 
- North Carolina
- North Dakota
- Oregon - six or more gallons
- Rhode Island
- South Carolina
- Washington - four or more gallons
In addition, the state of Utah does not have a keg registration law as such, however the state requires anyone in possession of a keg to obtain a temporary beer permit, and limits the use of kegs to low-alcohol beer only. 
Wagenaar, Alexander C.; Eileen M. Harwood; Cindy Silianoff; Traci L. Toomey (2005). "Measuring public police: The case of beer keg registration laws" (PDF). Evaluation and Program Policy 28 (28): 359–367. doi:10.1016/j.evalprogplan.2005.07.001. Retrieved 2006-09-05.
- Keg Registration Keg Registration laws have been passed in 26 of 50 states. See if your state is on the list.