Part of the problem, he argued, was that some economic transactions are so complicated, and involve so many things which could go wrong, that writing a legally enforceable contract that takes all possibilities into account is impossible.

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Economic growth is often associated with clear and enforceable property and contract rules.

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Washington is hardly unique in wanting a liberal world system of open trade, freedom of the seas, enforceable rules of contract and protection for foreign investment.

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"In our judgment the Union has no obligation to accept Mr. Hunter's current contract as valid or enforceable, " the statement read.

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Much would then depend on the legal jurisdiction of any contract as to whether it was actually enforceable.

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Carnival's contract prohibits a class action suit, but Hickey said he's not sure whether it is legally enforceable.

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