Sanke Keg sale legal?

I am using Sanke kegs for brewing which I converted into brew kettles. I bought these kegs used on Craigslist. All of them are from different breweries which I do not want to list here.
However someone told me that it is actually illegal to sell them since they are owned by the breweries. Since I am thinking of replacing one of them with a better brew kettle I wonder if I could get into trouble by trying to sell one of my on the internet like Craigslist.

Oh boy...

Maybe.

In most places, the breweries own the kegs and keeping the kegs for the deposit is illegal.

Sometimes the breweries sell off their old/damaged kegs, though, and you can purchase them legally.

This is worth discussing, but it comes up often and pretty soon it turns into a heated debate, full of gems like "it's only illegal if you don't get caught!"- so I'll close this thread now and encourage you to look around the forum for perspectives on this.