On this moral duty question, it occurred to me that it would be somewhat unfair to impose restictions on the manner in which the film rights may be exercised by a purchaser of those rights that:
- were not contemplated at the time he purchased the rights; and
- were not therefore taken into account in calculating the amount to be paid to the person selling those rights.
Quite apart from the fact that such restrictions would be unenforceable at law, it seems to me to be morally wrong to try to assert restrictions on the use of the rights when the author has been paid for those rights on the basis that such restrictions do not apply.