The first search result came up with this:

In 1994, Nick Szabo, a legal scholar, and cryptographer, realized that the decentralized ledger could be used for smart contracts, otherwise called self-executing contracts, blockchain contracts, or digital contracts. In this format, contracts could be converted to computer code, stored and replicated on the system and supervised by the network of computers that run the blockchain.

When a bitUSD margin gets called and is liquidated back into BitShares autonomously by the blockchain, why would that not be considered a "smart contract"?

Or maybe a better question would be, how do you define a smart contract?