In the United States, Article 2 of the Uniform Commercial Code displaces the traditional rule in an attempt to adjust the law of sales of goods to the realities of the modern commercial marketplace. If the goods are identified to the contract for sale and in the possession of the seller, a court may order that the goods be delivered over to the buyer upon payment of the price. This is termed replevin. In addition, the Code allows a court to order specific performance where "the goods are unique or in other proper circumstances", leaving the question of what circumstances are proper to be developed by case law. The relief of Specific Performance is an equitable relief which is usually remedial or protective in nature. In the civil law (the law of continental Europe and much of the non English speaking world) specific performance is considered to be the basic right. Money damages are a kind of "substitute specific performance." Indeed, it has been proposed that substitute specific performance better explains the common law rules of contract as well, see (Steven Smith, Contract Law, Clarenden Law ). In English law, in principle reparation must be done in specie unless another remedy is ‘more appropriate’. Legal debate There is an ongoing debate in the legal literature regarding the desirability of specific performance. Economists, generally, take the view that specific performance should be reserved to exceptional settings, because it is costly to administer and may deter promisors from engaging in efficient breach. Professor Steven Shavell, for example, famously argued that specific performance should only be reserved to contracts to convey property and that in all other cases, money damages would be superior. In contrast, many lawyers from other philosophical traditions take the view that specific performance should be preferred as it is closest to what was promised in the contract. There is also uncertainty arising from empirical research whether specific performance provides greater value to promisees than money damages, given the difficulties of enforcement. Law and economics In contract theory, economists have compared specific performance to at-will contracts. Suppose that a seller and a buyer have agreed to trade a good in the future. In the case of specific performance, delivery of the good can be mandated by the court, while in the case of at-will contracting, the seller always has the right to walk away from the contract. Hart and Moore