Is it legally sound to buy a car at an auction?

Not really. You have a brief period to visually inspect the car in a very minimal way. You cannot tell if there are major suspension, engine or transmission issues without driving the automobile. Stuff that's obvious will be easy for a knowledgeable person to spot, but be aware it's always a crap shoot. I've bough a few hundred cars at auction, and at least 10% had issues that were only discovered after the purchase. If you bought it for a lot less than it's actual cash value you may be OK. With today's sophisticated electronic computerized cars the first thing is the CHECK ENGINE light can be triggered by any one of a thousand causes some minor some major be ready to take that into consideration. Good Luck! <>Stan