It is illegal for a scrap metal dealer to purchase a beer keg without proof of ownership.

The Law Explained

Thirsty college students and local thieves often discovered that an empty aluminum beer keg could be traded at a scrap yard for quick cash. This led to a massive shortage of kegs for breweries, who were losing thousands of dollars to petty theft. The city implemented strict record-keeping rules to ensure the party favors weren't being fenced. You must now prove you actually own the keg before scrapping it.