So after three months what happens? It would seem that if breweries were concerned they would get law enforcement involved since it could involve criminal prosecution. Let's face it.....Big Beer doesn't really care about getting the kegs back or at least enough to actively pursue it.Regardless, not returning a keg is a civil issue, not a crime.
Actually, not returning a keg is considered to be crime (misappropriation) in many states. The states control deposits and the laws pertaining to kegs. It's part of the three-tier distribution system that was put into place after the repeal of Prohibition.
Here's Missouri's keg deposit law:
"3. Each retail licensee shall require each keg purchaser to present valid identification and a minimum deposit of fifty dollars per keg at the time of purchase. On the identification form provided by the division of alcohol and tobacco control the licensee shall record for each keg sale the date of sale, the size of keg, keg tag identification number, the amount of container deposit, the name, address, and date of birth of the purchaser, and the form of identification presented by such purchaser. The purchaser shall sign a statement at the time of purchase attesting to the accuracy of the purchaser's name and address and acknowledging that misuse of the keg or its contents may result in civil liability, criminal prosecution, or both. The licensee shall retain the identification form for a minimum of three months following the sale of the keg."