How can an ethereum contract be verified or enforced in the physical world? It seems like only things that can be programmatically checked are available for verification. If you agree to pay me 1 GardenCoin to weed your garden, how can I be sure that I will be paid after I weed your garden? What if I do a crappy job of it? How is this settled in the real world, especially where value judgment is involved?
Currently you will need a real world contract terms binding the parties to the outcome of your service matching ethereum contracts, because possibly no legislation will enforce fulfillment of a smart contract — at least as long as no influential entity wants to enforce it :D