The production of transgenic animals raises a number of legal or paralegal questions, both in the United States and in the international arena. E.g., in the United States it is legal to patent a transgenic animal, but in Europe it is not. This raises a number of issues. How different must two lines of transgenic animals be for separate patents to be issued? How are patents on livestock going to be enforced in a loosely regulated industry such as farming? What are the consequences in terms of international trade?